1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * serial_tegra.c
   4 *
   5 * High-speed serial driver for NVIDIA Tegra SoCs
   6 *
   7 * Copyright (c) 2012-2019, NVIDIA CORPORATION.  All rights reserved.
   8 *
   9 * Author: Laxman Dewangan <ldewangan@nvidia.com>
  10 */
  11
  12#include <linux/clk.h>
  13#include <linux/debugfs.h>
  14#include <linux/delay.h>
  15#include <linux/dmaengine.h>
  16#include <linux/dma-mapping.h>
  17#include <linux/dmapool.h>
  18#include <linux/err.h>
  19#include <linux/io.h>
  20#include <linux/irq.h>
  21#include <linux/module.h>
  22#include <linux/of.h>
  23#include <linux/pagemap.h>
  24#include <linux/platform_device.h>
  25#include <linux/reset.h>
  26#include <linux/serial.h>
  27#include <linux/serial_8250.h>
  28#include <linux/serial_core.h>
  29#include <linux/serial_reg.h>
  30#include <linux/slab.h>
  31#include <linux/string.h>
  32#include <linux/termios.h>
  33#include <linux/tty.h>
  34#include <linux/tty_flip.h>
  35
  36#define TEGRA_UART_TYPE				"TEGRA_UART"
  37#define TX_EMPTY_STATUS				(UART_LSR_TEMT | UART_LSR_THRE)
  38#define BYTES_TO_ALIGN(x)			((unsigned long)(x) & 0x3)
  39
  40#define TEGRA_UART_RX_DMA_BUFFER_SIZE		4096
  41#define TEGRA_UART_LSR_TXFIFO_FULL		0x100
  42#define TEGRA_UART_IER_EORD			0x20
  43#define TEGRA_UART_MCR_RTS_EN			0x40
  44#define TEGRA_UART_MCR_CTS_EN			0x20
  45#define TEGRA_UART_LSR_ANY			(UART_LSR_OE | UART_LSR_BI | \
  46						UART_LSR_PE | UART_LSR_FE)
  47#define TEGRA_UART_IRDA_CSR			0x08
  48#define TEGRA_UART_SIR_ENABLED			0x80
  49
  50#define TEGRA_UART_TX_PIO			1
  51#define TEGRA_UART_TX_DMA			2
  52#define TEGRA_UART_MIN_DMA			16
  53#define TEGRA_UART_FIFO_SIZE			32
  54
  55/*
  56 * Tx fifo trigger level setting in tegra uart is in
  57 * reverse way then conventional uart.
  58 */
  59#define TEGRA_UART_TX_TRIG_16B			0x00
  60#define TEGRA_UART_TX_TRIG_8B			0x10
  61#define TEGRA_UART_TX_TRIG_4B			0x20
  62#define TEGRA_UART_TX_TRIG_1B			0x30
  63
  64#define TEGRA_UART_MAXIMUM			8
  65
  66/* Default UART setting when started: 115200 no parity, stop, 8 data bits */
  67#define TEGRA_UART_DEFAULT_BAUD			115200
  68#define TEGRA_UART_DEFAULT_LSR			UART_LCR_WLEN8
  69
  70/* Tx transfer mode */
  71#define TEGRA_TX_PIO				1
  72#define TEGRA_TX_DMA				2
  73
  74#define TEGRA_UART_FCR_IIR_FIFO_EN		0x40
  75
  76/**
  77 * struct tegra_uart_chip_data: SOC specific data.
  78 *
  79 * @tx_fifo_full_status: Status flag available for checking tx fifo full.
  80 * @allow_txfifo_reset_fifo_mode: allow_tx fifo reset with fifo mode or not.
  81 *			Tegra30 does not allow this.
  82 * @support_clk_src_div: Clock source support the clock divider.
  83 * @fifo_mode_enable_status: Is FIFO mode enabled?
  84 * @uart_max_port: Maximum number of UART ports
  85 * @max_dma_burst_bytes: Maximum size of DMA bursts
  86 * @error_tolerance_low_range: Lowest number in the error tolerance range
  87 * @error_tolerance_high_range: Highest number in the error tolerance range
  88 */
  89struct tegra_uart_chip_data {
  90	bool	tx_fifo_full_status;
  91	bool	allow_txfifo_reset_fifo_mode;
  92	bool	support_clk_src_div;
  93	bool	fifo_mode_enable_status;
  94	int	uart_max_port;
  95	int	max_dma_burst_bytes;
  96	int	error_tolerance_low_range;
  97	int	error_tolerance_high_range;
  98};
  99
 100struct tegra_baud_tolerance {
 101	u32 lower_range_baud;
 102	u32 upper_range_baud;
 103	s32 tolerance;
 104};
 105
 106struct tegra_uart_port {
 107	struct uart_port			uport;
 108	const struct tegra_uart_chip_data	*cdata;
 109
 110	struct clk				*uart_clk;
 111	struct reset_control			*rst;
 112	unsigned int				current_baud;
 113
 114	/* Register shadow */
 115	unsigned long				fcr_shadow;
 116	unsigned long				mcr_shadow;
 117	unsigned long				lcr_shadow;
 118	unsigned long				ier_shadow;
 119	bool					rts_active;
 120
 121	int					tx_in_progress;
 122	unsigned int				tx_bytes;
 123
 124	bool					enable_modem_interrupt;
 125
 126	bool					rx_timeout;
 127	int					rx_in_progress;
 128	int					symb_bit;
 129
 130	struct dma_chan				*rx_dma_chan;
 131	struct dma_chan				*tx_dma_chan;
 132	dma_addr_t				rx_dma_buf_phys;
 133	dma_addr_t				tx_dma_buf_phys;
 134	unsigned char				*rx_dma_buf_virt;
 135	unsigned char				*tx_dma_buf_virt;
 136	struct dma_async_tx_descriptor		*tx_dma_desc;
 137	struct dma_async_tx_descriptor		*rx_dma_desc;
 138	dma_cookie_t				tx_cookie;
 139	dma_cookie_t				rx_cookie;
 140	unsigned int				tx_bytes_requested;
 141	unsigned int				rx_bytes_requested;
 142	struct tegra_baud_tolerance		*baud_tolerance;
 143	int					n_adjustable_baud_rates;
 144	int					required_rate;
 145	int					configured_rate;
 146	bool					use_rx_pio;
 147	bool					use_tx_pio;
 148	bool					rx_dma_active;
 149};
 150
 151static void tegra_uart_start_next_tx(struct tegra_uart_port *tup);
 152static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup);
 153static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,
 154					bool dma_to_memory);
 155
 156static inline unsigned long tegra_uart_read(struct tegra_uart_port *tup,
 157		unsigned long reg)
 158{
 159	return readl(tup->uport.membase + (reg << tup->uport.regshift));
 160}
 161
 162static inline void tegra_uart_write(struct tegra_uart_port *tup, unsigned val,
 163	unsigned long reg)
 164{
 165	writel(val, tup->uport.membase + (reg << tup->uport.regshift));
 166}
 167
 168static inline struct tegra_uart_port *to_tegra_uport(struct uart_port *u)
 169{
 170	return container_of(u, struct tegra_uart_port, uport);
 171}
 172
 173static unsigned int tegra_uart_get_mctrl(struct uart_port *u)
 174{
 175	struct tegra_uart_port *tup = to_tegra_uport(u);
 176
 177	/*
 178	 * RI - Ring detector is active
 179	 * CD/DCD/CAR - Carrier detect is always active. For some reason
 180	 *	linux has different names for carrier detect.
 181	 * DSR - Data Set ready is active as the hardware doesn't support it.
 182	 *	Don't know if the linux support this yet?
 183	 * CTS - Clear to send. Always set to active, as the hardware handles
 184	 *	CTS automatically.
 185	 */
 186	if (tup->enable_modem_interrupt)
 187		return TIOCM_RI | TIOCM_CD | TIOCM_DSR | TIOCM_CTS;
 188	return TIOCM_CTS;
 189}
 190
 191static void set_rts(struct tegra_uart_port *tup, bool active)
 192{
 193	unsigned long mcr;
 194
 195	mcr = tup->mcr_shadow;
 196	if (active)
 197		mcr |= TEGRA_UART_MCR_RTS_EN;
 198	else
 199		mcr &= ~TEGRA_UART_MCR_RTS_EN;
 200	if (mcr != tup->mcr_shadow) {
 201		tegra_uart_write(tup, mcr, UART_MCR);
 202		tup->mcr_shadow = mcr;
 203	}
 204}
 205
 206static void set_dtr(struct tegra_uart_port *tup, bool active)
 207{
 208	unsigned long mcr;
 209
 210	mcr = tup->mcr_shadow;
 211	if (active)
 212		mcr |= UART_MCR_DTR;
 213	else
 214		mcr &= ~UART_MCR_DTR;
 215	if (mcr != tup->mcr_shadow) {
 216		tegra_uart_write(tup, mcr, UART_MCR);
 217		tup->mcr_shadow = mcr;
 218	}
 219}
 220
 221static void set_loopbk(struct tegra_uart_port *tup, bool active)
 222{
 223	unsigned long mcr = tup->mcr_shadow;
 224
 225	if (active)
 226		mcr |= UART_MCR_LOOP;
 227	else
 228		mcr &= ~UART_MCR_LOOP;
 229
 230	if (mcr != tup->mcr_shadow) {
 231		tegra_uart_write(tup, mcr, UART_MCR);
 232		tup->mcr_shadow = mcr;
 233	}
 234}
 235
 236static void tegra_uart_set_mctrl(struct uart_port *u, unsigned int mctrl)
 237{
 238	struct tegra_uart_port *tup = to_tegra_uport(u);
 239	int enable;
 240
 241	tup->rts_active = !!(mctrl & TIOCM_RTS);
 242	set_rts(tup, tup->rts_active);
 243
 244	enable = !!(mctrl & TIOCM_DTR);
 245	set_dtr(tup, enable);
 246
 247	enable = !!(mctrl & TIOCM_LOOP);
 248	set_loopbk(tup, enable);
 249}
 250
 251static void tegra_uart_break_ctl(struct uart_port *u, int break_ctl)
 252{
 253	struct tegra_uart_port *tup = to_tegra_uport(u);
 254	unsigned long lcr;
 255
 256	lcr = tup->lcr_shadow;
 257	if (break_ctl)
 258		lcr |= UART_LCR_SBC;
 259	else
 260		lcr &= ~UART_LCR_SBC;
 261	tegra_uart_write(tup, lcr, UART_LCR);
 262	tup->lcr_shadow = lcr;
 263}
 264
 265/**
 266 * tegra_uart_wait_cycle_time: Wait for N UART clock periods
 267 *
 268 * @tup:	Tegra serial port data structure.
 269 * @cycles:	Number of clock periods to wait.
 270 *
 271 * Tegra UARTs are clocked at 16X the baud/bit rate and hence the UART
 272 * clock speed is 16X the current baud rate.
 273 */
 274static void tegra_uart_wait_cycle_time(struct tegra_uart_port *tup,
 275				       unsigned int cycles)
 276{
 277	if (tup->current_baud)
 278		udelay(DIV_ROUND_UP(cycles * 1000000, tup->current_baud * 16));
 279}
 280
 281/* Wait for a symbol-time. */
 282static void tegra_uart_wait_sym_time(struct tegra_uart_port *tup,
 283		unsigned int syms)
 284{
 285	if (tup->current_baud)
 286		udelay(DIV_ROUND_UP(syms * tup->symb_bit * 1000000,
 287			tup->current_baud));
 288}
 289
 290static int tegra_uart_wait_fifo_mode_enabled(struct tegra_uart_port *tup)
 291{
 292	unsigned long iir;
 293	unsigned int tmout = 100;
 294
 295	do {
 296		iir = tegra_uart_read(tup, UART_IIR);
 297		if (iir & TEGRA_UART_FCR_IIR_FIFO_EN)
 298			return 0;
 299		udelay(1);
 300	} while (--tmout);
 301
 302	return -ETIMEDOUT;
 303}
 304
 305static void tegra_uart_fifo_reset(struct tegra_uart_port *tup, u8 fcr_bits)
 306{
 307	unsigned long fcr = tup->fcr_shadow;
 308	unsigned int lsr, tmout = 10000;
 309
 310	if (tup->rts_active)
 311		set_rts(tup, false);
 312
 313	if (tup->cdata->allow_txfifo_reset_fifo_mode) {
 314		fcr |= fcr_bits & (UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
 315		tegra_uart_write(tup, fcr, UART_FCR);
 316	} else {
 317		fcr &= ~UART_FCR_ENABLE_FIFO;
 318		tegra_uart_write(tup, fcr, UART_FCR);
 319		udelay(60);
 320		fcr |= fcr_bits & (UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
 321		tegra_uart_write(tup, fcr, UART_FCR);
 322		fcr |= UART_FCR_ENABLE_FIFO;
 323		tegra_uart_write(tup, fcr, UART_FCR);
 324		if (tup->cdata->fifo_mode_enable_status)
 325			tegra_uart_wait_fifo_mode_enabled(tup);
 326	}
 327
 328	/* Dummy read to ensure the write is posted */
 329	tegra_uart_read(tup, UART_SCR);
 330
 331	/*
 332	 * For all tegra devices (up to t210), there is a hardware issue that
 333	 * requires software to wait for 32 UART clock periods for the flush
 334	 * to propagate, otherwise data could be lost.
 335	 */
 336	tegra_uart_wait_cycle_time(tup, 32);
 337
 338	do {
 339		lsr = tegra_uart_read(tup, UART_LSR);
 340		if ((lsr & UART_LSR_TEMT) && !(lsr & UART_LSR_DR))
 341			break;
 342		udelay(1);
 343	} while (--tmout);
 344
 345	if (tup->rts_active)
 346		set_rts(tup, true);
 347}
 348
 349static long tegra_get_tolerance_rate(struct tegra_uart_port *tup,
 350				     unsigned int baud, long rate)
 351{
 352	int i;
 353
 354	for (i = 0; i < tup->n_adjustable_baud_rates; ++i) {
 355		if (baud >= tup->baud_tolerance[i].lower_range_baud &&
 356		    baud <= tup->baud_tolerance[i].upper_range_baud)
 357			return (rate + (rate *
 358				tup->baud_tolerance[i].tolerance) / 10000);
 359	}
 360
 361	return rate;
 362}
 363
 364static int tegra_check_rate_in_range(struct tegra_uart_port *tup)
 365{
 366	long diff;
 367
 368	diff = ((long)(tup->configured_rate - tup->required_rate) * 10000)
 369		/ tup->required_rate;
 370	if (diff < (tup->cdata->error_tolerance_low_range * 100) ||
 371	    diff > (tup->cdata->error_tolerance_high_range * 100)) {
 372		dev_err(tup->uport.dev,
 373			"configured baud rate is out of range by %ld", diff);
 374		return -EIO;
 375	}
 376
 377	return 0;
 378}
 379
 380static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
 381{
 382	unsigned long rate;
 383	unsigned int divisor;
 384	unsigned long lcr;
 385	unsigned long flags;
 386	int ret;
 387
 388	if (tup->current_baud == baud)
 389		return 0;
 390
 391	if (tup->cdata->support_clk_src_div) {
 392		rate = baud * 16;
 393		tup->required_rate = rate;
 394
 395		if (tup->n_adjustable_baud_rates)
 396			rate = tegra_get_tolerance_rate(tup, baud, rate);
 397
 398		ret = clk_set_rate(tup->uart_clk, rate);
 399		if (ret < 0) {
 400			dev_err(tup->uport.dev,
 401				"clk_set_rate() failed for rate %lu\n", rate);
 402			return ret;
 403		}
 404		tup->configured_rate = clk_get_rate(tup->uart_clk);
 405		divisor = 1;
 406		ret = tegra_check_rate_in_range(tup);
 407		if (ret < 0)
 408			return ret;
 409	} else {
 410		rate = clk_get_rate(tup->uart_clk);
 411		divisor = DIV_ROUND_CLOSEST(rate, baud * 16);
 412	}
 413
 414	uart_port_lock_irqsave(&tup->uport, &flags);
 415	lcr = tup->lcr_shadow;
 416	lcr |= UART_LCR_DLAB;
 417	tegra_uart_write(tup, lcr, UART_LCR);
 418
 419	tegra_uart_write(tup, divisor & 0xFF, UART_TX);
 420	tegra_uart_write(tup, ((divisor >> 8) & 0xFF), UART_IER);
 421
 422	lcr &= ~UART_LCR_DLAB;
 423	tegra_uart_write(tup, lcr, UART_LCR);
 424
 425	/* Dummy read to ensure the write is posted */
 426	tegra_uart_read(tup, UART_SCR);
 427	uart_port_unlock_irqrestore(&tup->uport, flags);
 428
 429	tup->current_baud = baud;
 430
 431	/* wait two character intervals at new rate */
 432	tegra_uart_wait_sym_time(tup, 2);
 433	return 0;
 434}
 435
 436static u8 tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
 437			unsigned long lsr)
 438{
 439	u8 flag = TTY_NORMAL;
 440
 441	if (unlikely(lsr & TEGRA_UART_LSR_ANY)) {
 442		if (lsr & UART_LSR_OE) {
 443			/* Overrun error */
 444			flag = TTY_OVERRUN;
 445			tup->uport.icount.overrun++;
 446			dev_dbg(tup->uport.dev, "Got overrun errors\n");
 447		} else if (lsr & UART_LSR_PE) {
 448			/* Parity error */
 449			flag = TTY_PARITY;
 450			tup->uport.icount.parity++;
 451			dev_dbg(tup->uport.dev, "Got Parity errors\n");
 452		} else if (lsr & UART_LSR_FE) {
 453			flag = TTY_FRAME;
 454			tup->uport.icount.frame++;
 455			dev_dbg(tup->uport.dev, "Got frame errors\n");
 456		} else if (lsr & UART_LSR_BI) {
 457			/*
 458			 * Break error
 459			 * If FIFO read error without any data, reset Rx FIFO
 460			 */
 461			if (!(lsr & UART_LSR_DR) && (lsr & UART_LSR_FIFOE))
 462				tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_RCVR);
 463			if (tup->uport.ignore_status_mask & UART_LSR_BI)
 464				return TTY_BREAK;
 465			flag = TTY_BREAK;
 466			tup->uport.icount.brk++;
 467			dev_dbg(tup->uport.dev, "Got Break\n");
 468		}
 469		uart_insert_char(&tup->uport, lsr, UART_LSR_OE, 0, flag);
 470	}
 471
 472	return flag;
 473}
 474
 475static int tegra_uart_request_port(struct uart_port *u)
 476{
 477	return 0;
 478}
 479
 480static void tegra_uart_release_port(struct uart_port *u)
 481{
 482	/* Nothing to do here */
 483}
 484
 485static void tegra_uart_fill_tx_fifo(struct tegra_uart_port *tup, int max_bytes)
 486{
 487	struct circ_buf *xmit = &tup->uport.state->xmit;
 488	int i;
 489
 490	for (i = 0; i < max_bytes; i++) {
 491		BUG_ON(uart_circ_empty(xmit));
 492		if (tup->cdata->tx_fifo_full_status) {
 493			unsigned long lsr = tegra_uart_read(tup, UART_LSR);
 494			if ((lsr & TEGRA_UART_LSR_TXFIFO_FULL))
 495				break;
 496		}
 497		tegra_uart_write(tup, xmit->buf[xmit->tail], UART_TX);
 498		uart_xmit_advance(&tup->uport, 1);
 
 499	}
 500}
 501
 502static void tegra_uart_start_pio_tx(struct tegra_uart_port *tup,
 503		unsigned int bytes)
 504{
 505	if (bytes > TEGRA_UART_MIN_DMA)
 506		bytes = TEGRA_UART_MIN_DMA;
 507
 508	tup->tx_in_progress = TEGRA_UART_TX_PIO;
 509	tup->tx_bytes = bytes;
 510	tup->ier_shadow |= UART_IER_THRI;
 511	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
 512}
 513
 514static void tegra_uart_tx_dma_complete(void *args)
 515{
 516	struct tegra_uart_port *tup = args;
 517	struct circ_buf *xmit = &tup->uport.state->xmit;
 518	struct dma_tx_state state;
 519	unsigned long flags;
 520	unsigned int count;
 521
 522	dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
 523	count = tup->tx_bytes_requested - state.residue;
 524	async_tx_ack(tup->tx_dma_desc);
 525	uart_port_lock_irqsave(&tup->uport, &flags);
 526	uart_xmit_advance(&tup->uport, count);
 527	tup->tx_in_progress = 0;
 528	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 529		uart_write_wakeup(&tup->uport);
 530	tegra_uart_start_next_tx(tup);
 531	uart_port_unlock_irqrestore(&tup->uport, flags);
 532}
 533
 534static int tegra_uart_start_tx_dma(struct tegra_uart_port *tup,
 535		unsigned long count)
 536{
 537	struct circ_buf *xmit = &tup->uport.state->xmit;
 538	dma_addr_t tx_phys_addr;
 
 539
 540	tup->tx_bytes = count & ~(0xF);
 541	tx_phys_addr = tup->tx_dma_buf_phys + xmit->tail;
 
 
 542
 543	dma_sync_single_for_device(tup->uport.dev, tx_phys_addr,
 544				   tup->tx_bytes, DMA_TO_DEVICE);
 545
 546	tup->tx_dma_desc = dmaengine_prep_slave_single(tup->tx_dma_chan,
 547				tx_phys_addr, tup->tx_bytes, DMA_MEM_TO_DEV,
 548				DMA_PREP_INTERRUPT);
 549	if (!tup->tx_dma_desc) {
 550		dev_err(tup->uport.dev, "Not able to get desc for Tx\n");
 551		return -EIO;
 552	}
 553
 554	tup->tx_dma_desc->callback = tegra_uart_tx_dma_complete;
 555	tup->tx_dma_desc->callback_param = tup;
 556	tup->tx_in_progress = TEGRA_UART_TX_DMA;
 557	tup->tx_bytes_requested = tup->tx_bytes;
 558	tup->tx_cookie = dmaengine_submit(tup->tx_dma_desc);
 559	dma_async_issue_pending(tup->tx_dma_chan);
 560	return 0;
 561}
 562
 563static void tegra_uart_start_next_tx(struct tegra_uart_port *tup)
 564{
 
 
 565	unsigned long tail;
 566	unsigned long count;
 567	struct circ_buf *xmit = &tup->uport.state->xmit;
 568
 569	if (!tup->current_baud)
 570		return;
 571
 572	tail = (unsigned long)&xmit->buf[xmit->tail];
 573	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
 574	if (!count)
 575		return;
 576
 
 
 577	if (tup->use_tx_pio || count < TEGRA_UART_MIN_DMA)
 578		tegra_uart_start_pio_tx(tup, count);
 579	else if (BYTES_TO_ALIGN(tail) > 0)
 580		tegra_uart_start_pio_tx(tup, BYTES_TO_ALIGN(tail));
 581	else
 582		tegra_uart_start_tx_dma(tup, count);
 583}
 584
 585/* Called by serial core driver with u->lock taken. */
 586static void tegra_uart_start_tx(struct uart_port *u)
 587{
 588	struct tegra_uart_port *tup = to_tegra_uport(u);
 589	struct circ_buf *xmit = &u->state->xmit;
 590
 591	if (!uart_circ_empty(xmit) && !tup->tx_in_progress)
 592		tegra_uart_start_next_tx(tup);
 593}
 594
 595static unsigned int tegra_uart_tx_empty(struct uart_port *u)
 596{
 597	struct tegra_uart_port *tup = to_tegra_uport(u);
 598	unsigned int ret = 0;
 599	unsigned long flags;
 600
 601	uart_port_lock_irqsave(u, &flags);
 602	if (!tup->tx_in_progress) {
 603		unsigned long lsr = tegra_uart_read(tup, UART_LSR);
 604		if ((lsr & TX_EMPTY_STATUS) == TX_EMPTY_STATUS)
 605			ret = TIOCSER_TEMT;
 606	}
 607	uart_port_unlock_irqrestore(u, flags);
 608	return ret;
 609}
 610
 611static void tegra_uart_stop_tx(struct uart_port *u)
 612{
 613	struct tegra_uart_port *tup = to_tegra_uport(u);
 614	struct dma_tx_state state;
 615	unsigned int count;
 616
 617	if (tup->tx_in_progress != TEGRA_UART_TX_DMA)
 618		return;
 619
 620	dmaengine_pause(tup->tx_dma_chan);
 621	dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
 622	dmaengine_terminate_all(tup->tx_dma_chan);
 623	count = tup->tx_bytes_requested - state.residue;
 624	async_tx_ack(tup->tx_dma_desc);
 625	uart_xmit_advance(&tup->uport, count);
 626	tup->tx_in_progress = 0;
 627}
 628
 629static void tegra_uart_handle_tx_pio(struct tegra_uart_port *tup)
 630{
 631	struct circ_buf *xmit = &tup->uport.state->xmit;
 632
 633	tegra_uart_fill_tx_fifo(tup, tup->tx_bytes);
 634	tup->tx_in_progress = 0;
 635	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 636		uart_write_wakeup(&tup->uport);
 637	tegra_uart_start_next_tx(tup);
 638}
 639
 640static void tegra_uart_handle_rx_pio(struct tegra_uart_port *tup,
 641		struct tty_port *port)
 642{
 643	do {
 644		unsigned long lsr = 0;
 645		u8 ch, flag = TTY_NORMAL;
 646
 647		lsr = tegra_uart_read(tup, UART_LSR);
 648		if (!(lsr & UART_LSR_DR))
 649			break;
 650
 651		flag = tegra_uart_decode_rx_error(tup, lsr);
 652		if (flag != TTY_NORMAL)
 653			continue;
 654
 655		ch = (unsigned char) tegra_uart_read(tup, UART_RX);
 656		tup->uport.icount.rx++;
 657
 658		if (uart_handle_sysrq_char(&tup->uport, ch))
 659			continue;
 660
 661		if (tup->uport.ignore_status_mask & UART_LSR_DR)
 662			continue;
 663
 664		tty_insert_flip_char(port, ch, flag);
 665	} while (1);
 666}
 667
 668static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
 669				      struct tty_port *port,
 670				      unsigned int count)
 671{
 672	int copied;
 673
 674	/* If count is zero, then there is no data to be copied */
 675	if (!count)
 676		return;
 677
 678	tup->uport.icount.rx += count;
 679
 680	if (tup->uport.ignore_status_mask & UART_LSR_DR)
 681		return;
 682
 683	dma_sync_single_for_cpu(tup->uport.dev, tup->rx_dma_buf_phys,
 684				count, DMA_FROM_DEVICE);
 685	copied = tty_insert_flip_string(port,
 686			((unsigned char *)(tup->rx_dma_buf_virt)), count);
 687	if (copied != count) {
 688		WARN_ON(1);
 689		dev_err(tup->uport.dev, "RxData copy to tty layer failed\n");
 690	}
 691	dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
 692				   count, DMA_TO_DEVICE);
 693}
 694
 695static void do_handle_rx_pio(struct tegra_uart_port *tup)
 696{
 697	struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
 698	struct tty_port *port = &tup->uport.state->port;
 699
 700	tegra_uart_handle_rx_pio(tup, port);
 701	if (tty) {
 702		tty_flip_buffer_push(port);
 703		tty_kref_put(tty);
 704	}
 705}
 706
 707static void tegra_uart_rx_buffer_push(struct tegra_uart_port *tup,
 708				      unsigned int residue)
 709{
 710	struct tty_port *port = &tup->uport.state->port;
 711	unsigned int count;
 712
 713	async_tx_ack(tup->rx_dma_desc);
 714	count = tup->rx_bytes_requested - residue;
 715
 716	/* If we are here, DMA is stopped */
 717	tegra_uart_copy_rx_to_tty(tup, port, count);
 718
 719	do_handle_rx_pio(tup);
 720}
 721
 722static void tegra_uart_rx_dma_complete(void *args)
 723{
 724	struct tegra_uart_port *tup = args;
 725	struct uart_port *u = &tup->uport;
 726	unsigned long flags;
 727	struct dma_tx_state state;
 728	enum dma_status status;
 729
 730	uart_port_lock_irqsave(u, &flags);
 731
 732	status = dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
 733
 734	if (status == DMA_IN_PROGRESS) {
 735		dev_dbg(tup->uport.dev, "RX DMA is in progress\n");
 736		goto done;
 737	}
 738
 739	/* Deactivate flow control to stop sender */
 740	if (tup->rts_active)
 741		set_rts(tup, false);
 742
 743	tup->rx_dma_active = false;
 744	tegra_uart_rx_buffer_push(tup, 0);
 745	tegra_uart_start_rx_dma(tup);
 746
 747	/* Activate flow control to start transfer */
 748	if (tup->rts_active)
 749		set_rts(tup, true);
 750
 751done:
 752	uart_port_unlock_irqrestore(u, flags);
 753}
 754
 755static void tegra_uart_terminate_rx_dma(struct tegra_uart_port *tup)
 756{
 757	struct dma_tx_state state;
 758
 759	if (!tup->rx_dma_active) {
 760		do_handle_rx_pio(tup);
 761		return;
 762	}
 763
 764	dmaengine_pause(tup->rx_dma_chan);
 765	dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
 766	dmaengine_terminate_all(tup->rx_dma_chan);
 767
 768	tegra_uart_rx_buffer_push(tup, state.residue);
 769	tup->rx_dma_active = false;
 770}
 771
 772static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup)
 773{
 774	/* Deactivate flow control to stop sender */
 775	if (tup->rts_active)
 776		set_rts(tup, false);
 777
 778	tegra_uart_terminate_rx_dma(tup);
 779
 780	if (tup->rts_active)
 781		set_rts(tup, true);
 782}
 783
 784static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup)
 785{
 786	unsigned int count = TEGRA_UART_RX_DMA_BUFFER_SIZE;
 787
 788	if (tup->rx_dma_active)
 789		return 0;
 790
 791	tup->rx_dma_desc = dmaengine_prep_slave_single(tup->rx_dma_chan,
 792				tup->rx_dma_buf_phys, count, DMA_DEV_TO_MEM,
 793				DMA_PREP_INTERRUPT);
 794	if (!tup->rx_dma_desc) {
 795		dev_err(tup->uport.dev, "Not able to get desc for Rx\n");
 796		return -EIO;
 797	}
 798
 799	tup->rx_dma_active = true;
 800	tup->rx_dma_desc->callback = tegra_uart_rx_dma_complete;
 801	tup->rx_dma_desc->callback_param = tup;
 802	tup->rx_bytes_requested = count;
 803	tup->rx_cookie = dmaengine_submit(tup->rx_dma_desc);
 804	dma_async_issue_pending(tup->rx_dma_chan);
 805	return 0;
 806}
 807
 808static void tegra_uart_handle_modem_signal_change(struct uart_port *u)
 809{
 810	struct tegra_uart_port *tup = to_tegra_uport(u);
 811	unsigned long msr;
 812
 813	msr = tegra_uart_read(tup, UART_MSR);
 814	if (!(msr & UART_MSR_ANY_DELTA))
 815		return;
 816
 817	if (msr & UART_MSR_TERI)
 818		tup->uport.icount.rng++;
 819	if (msr & UART_MSR_DDSR)
 820		tup->uport.icount.dsr++;
 821	/* We may only get DDCD when HW init and reset */
 822	if (msr & UART_MSR_DDCD)
 823		uart_handle_dcd_change(&tup->uport, msr & UART_MSR_DCD);
 824	/* Will start/stop_tx accordingly */
 825	if (msr & UART_MSR_DCTS)
 826		uart_handle_cts_change(&tup->uport, msr & UART_MSR_CTS);
 827}
 828
 829static irqreturn_t tegra_uart_isr(int irq, void *data)
 830{
 831	struct tegra_uart_port *tup = data;
 832	struct uart_port *u = &tup->uport;
 833	unsigned long iir;
 834	unsigned long ier;
 835	bool is_rx_start = false;
 836	bool is_rx_int = false;
 837	unsigned long flags;
 838
 839	uart_port_lock_irqsave(u, &flags);
 840	while (1) {
 841		iir = tegra_uart_read(tup, UART_IIR);
 842		if (iir & UART_IIR_NO_INT) {
 843			if (!tup->use_rx_pio && is_rx_int) {
 844				tegra_uart_handle_rx_dma(tup);
 845				if (tup->rx_in_progress) {
 846					ier = tup->ier_shadow;
 847					ier |= (UART_IER_RLSI | UART_IER_RTOIE |
 848						TEGRA_UART_IER_EORD | UART_IER_RDI);
 849					tup->ier_shadow = ier;
 850					tegra_uart_write(tup, ier, UART_IER);
 851				}
 852			} else if (is_rx_start) {
 853				tegra_uart_start_rx_dma(tup);
 854			}
 855			uart_port_unlock_irqrestore(u, flags);
 856			return IRQ_HANDLED;
 857		}
 858
 859		switch ((iir >> 1) & 0x7) {
 860		case 0: /* Modem signal change interrupt */
 861			tegra_uart_handle_modem_signal_change(u);
 862			break;
 863
 864		case 1: /* Transmit interrupt only triggered when using PIO */
 865			tup->ier_shadow &= ~UART_IER_THRI;
 866			tegra_uart_write(tup, tup->ier_shadow, UART_IER);
 867			tegra_uart_handle_tx_pio(tup);
 868			break;
 869
 870		case 4: /* End of data */
 871		case 6: /* Rx timeout */
 872			if (!tup->use_rx_pio) {
 873				is_rx_int = tup->rx_in_progress;
 874				/* Disable Rx interrupts */
 875				ier = tup->ier_shadow;
 876				ier &= ~(UART_IER_RDI | UART_IER_RLSI |
 877					UART_IER_RTOIE | TEGRA_UART_IER_EORD);
 878				tup->ier_shadow = ier;
 879				tegra_uart_write(tup, ier, UART_IER);
 880				break;
 881			}
 882			fallthrough;
 883		case 2: /* Receive */
 884			if (!tup->use_rx_pio) {
 885				is_rx_start = tup->rx_in_progress;
 886				tup->ier_shadow  &= ~UART_IER_RDI;
 887				tegra_uart_write(tup, tup->ier_shadow,
 888						 UART_IER);
 889			} else {
 890				do_handle_rx_pio(tup);
 891			}
 892			break;
 893
 894		case 3: /* Receive error */
 895			tegra_uart_decode_rx_error(tup,
 896					tegra_uart_read(tup, UART_LSR));
 897			break;
 898
 899		case 5: /* break nothing to handle */
 900		case 7: /* break nothing to handle */
 901			break;
 902		}
 903	}
 904}
 905
 906static void tegra_uart_stop_rx(struct uart_port *u)
 907{
 908	struct tegra_uart_port *tup = to_tegra_uport(u);
 909	struct tty_port *port = &tup->uport.state->port;
 910	unsigned long ier;
 911
 912	if (tup->rts_active)
 913		set_rts(tup, false);
 914
 915	if (!tup->rx_in_progress)
 916		return;
 917
 918	tegra_uart_wait_sym_time(tup, 1); /* wait one character interval */
 919
 920	ier = tup->ier_shadow;
 921	ier &= ~(UART_IER_RDI | UART_IER_RLSI | UART_IER_RTOIE |
 922					TEGRA_UART_IER_EORD);
 923	tup->ier_shadow = ier;
 924	tegra_uart_write(tup, ier, UART_IER);
 925	tup->rx_in_progress = 0;
 926
 927	if (!tup->use_rx_pio)
 928		tegra_uart_terminate_rx_dma(tup);
 929	else
 930		tegra_uart_handle_rx_pio(tup, port);
 931}
 932
 933static void tegra_uart_hw_deinit(struct tegra_uart_port *tup)
 934{
 935	unsigned long flags;
 936	unsigned long char_time = DIV_ROUND_UP(10000000, tup->current_baud);
 937	unsigned long fifo_empty_time = tup->uport.fifosize * char_time;
 938	unsigned long wait_time;
 939	unsigned long lsr;
 940	unsigned long msr;
 941	unsigned long mcr;
 942
 943	/* Disable interrupts */
 944	tegra_uart_write(tup, 0, UART_IER);
 945
 946	lsr = tegra_uart_read(tup, UART_LSR);
 947	if ((lsr & UART_LSR_TEMT) != UART_LSR_TEMT) {
 948		msr = tegra_uart_read(tup, UART_MSR);
 949		mcr = tegra_uart_read(tup, UART_MCR);
 950		if ((mcr & TEGRA_UART_MCR_CTS_EN) && (msr & UART_MSR_CTS))
 951			dev_err(tup->uport.dev,
 952				"Tx Fifo not empty, CTS disabled, waiting\n");
 953
 954		/* Wait for Tx fifo to be empty */
 955		while ((lsr & UART_LSR_TEMT) != UART_LSR_TEMT) {
 956			wait_time = min(fifo_empty_time, 100lu);
 957			udelay(wait_time);
 958			fifo_empty_time -= wait_time;
 959			if (!fifo_empty_time) {
 960				msr = tegra_uart_read(tup, UART_MSR);
 961				mcr = tegra_uart_read(tup, UART_MCR);
 962				if ((mcr & TEGRA_UART_MCR_CTS_EN) &&
 963					(msr & UART_MSR_CTS))
 964					dev_err(tup->uport.dev,
 965						"Slave not ready\n");
 966				break;
 967			}
 968			lsr = tegra_uart_read(tup, UART_LSR);
 969		}
 970	}
 971
 972	uart_port_lock_irqsave(&tup->uport, &flags);
 973	/* Reset the Rx and Tx FIFOs */
 974	tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
 975	tup->current_baud = 0;
 976	uart_port_unlock_irqrestore(&tup->uport, flags);
 977
 978	tup->rx_in_progress = 0;
 979	tup->tx_in_progress = 0;
 980
 981	if (!tup->use_rx_pio)
 982		tegra_uart_dma_channel_free(tup, true);
 983	if (!tup->use_tx_pio)
 984		tegra_uart_dma_channel_free(tup, false);
 985
 986	clk_disable_unprepare(tup->uart_clk);
 987}
 988
 989static int tegra_uart_hw_init(struct tegra_uart_port *tup)
 990{
 991	int ret;
 992
 993	tup->fcr_shadow = 0;
 994	tup->mcr_shadow = 0;
 995	tup->lcr_shadow = 0;
 996	tup->ier_shadow = 0;
 997	tup->current_baud = 0;
 998
 999	ret = clk_prepare_enable(tup->uart_clk);
1000	if (ret) {
1001		dev_err(tup->uport.dev, "could not enable clk\n");
1002		return ret;
1003	}
1004
1005	/* Reset the UART controller to clear all previous status.*/
1006	reset_control_assert(tup->rst);
1007	udelay(10);
1008	reset_control_deassert(tup->rst);
1009
1010	tup->rx_in_progress = 0;
1011	tup->tx_in_progress = 0;
1012
1013	/*
1014	 * Set the trigger level
1015	 *
1016	 * For PIO mode:
1017	 *
1018	 * For receive, this will interrupt the CPU after that many number of
1019	 * bytes are received, for the remaining bytes the receive timeout
1020	 * interrupt is received. Rx high watermark is set to 4.
1021	 *
1022	 * For transmit, if the trasnmit interrupt is enabled, this will
1023	 * interrupt the CPU when the number of entries in the FIFO reaches the
1024	 * low watermark. Tx low watermark is set to 16 bytes.
1025	 *
1026	 * For DMA mode:
1027	 *
1028	 * Set the Tx trigger to 16. This should match the DMA burst size that
1029	 * programmed in the DMA registers.
1030	 */
1031	tup->fcr_shadow = UART_FCR_ENABLE_FIFO;
1032
1033	if (tup->use_rx_pio) {
1034		tup->fcr_shadow |= UART_FCR_R_TRIG_11;
1035	} else {
1036		if (tup->cdata->max_dma_burst_bytes == 8)
1037			tup->fcr_shadow |= UART_FCR_R_TRIG_10;
1038		else
1039			tup->fcr_shadow |= UART_FCR_R_TRIG_01;
1040	}
1041
1042	tup->fcr_shadow |= TEGRA_UART_TX_TRIG_16B;
1043	tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
1044
1045	/* Dummy read to ensure the write is posted */
1046	tegra_uart_read(tup, UART_SCR);
1047
1048	if (tup->cdata->fifo_mode_enable_status) {
1049		ret = tegra_uart_wait_fifo_mode_enabled(tup);
1050		if (ret < 0) {
1051			clk_disable_unprepare(tup->uart_clk);
1052			dev_err(tup->uport.dev,
1053				"Failed to enable FIFO mode: %d\n", ret);
1054			return ret;
1055		}
1056	} else {
1057		/*
1058		 * For all tegra devices (up to t210), there is a hardware
1059		 * issue that requires software to wait for 3 UART clock
1060		 * periods after enabling the TX fifo, otherwise data could
1061		 * be lost.
1062		 */
1063		tegra_uart_wait_cycle_time(tup, 3);
1064	}
1065
1066	/*
1067	 * Initialize the UART with default configuration
1068	 * (115200, N, 8, 1) so that the receive DMA buffer may be
1069	 * enqueued
1070	 */
1071	ret = tegra_set_baudrate(tup, TEGRA_UART_DEFAULT_BAUD);
1072	if (ret < 0) {
1073		clk_disable_unprepare(tup->uart_clk);
1074		dev_err(tup->uport.dev, "Failed to set baud rate\n");
1075		return ret;
1076	}
1077	if (!tup->use_rx_pio) {
1078		tup->lcr_shadow = TEGRA_UART_DEFAULT_LSR;
1079		tup->fcr_shadow |= UART_FCR_DMA_SELECT;
1080		tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
1081	} else {
1082		tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
1083	}
1084	tup->rx_in_progress = 1;
1085
1086	/*
1087	 * Enable IE_RXS for the receive status interrupts like line errors.
1088	 * Enable IE_RX_TIMEOUT to get the bytes which cannot be DMA'd.
1089	 *
1090	 * EORD is different interrupt than RX_TIMEOUT - RX_TIMEOUT occurs when
1091	 * the DATA is sitting in the FIFO and couldn't be transferred to the
1092	 * DMA as the DMA size alignment (4 bytes) is not met. EORD will be
1093	 * triggered when there is a pause of the incomming data stream for 4
1094	 * characters long.
1095	 *
1096	 * For pauses in the data which is not aligned to 4 bytes, we get
1097	 * both the EORD as well as RX_TIMEOUT - SW sees RX_TIMEOUT first
1098	 * then the EORD.
1099	 */
1100	tup->ier_shadow = UART_IER_RLSI | UART_IER_RTOIE | UART_IER_RDI;
1101
1102	/*
1103	 * If using DMA mode, enable EORD interrupt to notify about RX
1104	 * completion.
1105	 */
1106	if (!tup->use_rx_pio)
1107		tup->ier_shadow |= TEGRA_UART_IER_EORD;
1108
1109	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
1110	return 0;
1111}
1112
1113static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,
1114		bool dma_to_memory)
1115{
1116	if (dma_to_memory) {
1117		dmaengine_terminate_all(tup->rx_dma_chan);
1118		dma_release_channel(tup->rx_dma_chan);
1119		dma_free_coherent(tup->uport.dev, TEGRA_UART_RX_DMA_BUFFER_SIZE,
1120				tup->rx_dma_buf_virt, tup->rx_dma_buf_phys);
1121		tup->rx_dma_chan = NULL;
1122		tup->rx_dma_buf_phys = 0;
1123		tup->rx_dma_buf_virt = NULL;
1124	} else {
1125		dmaengine_terminate_all(tup->tx_dma_chan);
1126		dma_release_channel(tup->tx_dma_chan);
1127		dma_unmap_single(tup->uport.dev, tup->tx_dma_buf_phys,
1128			UART_XMIT_SIZE, DMA_TO_DEVICE);
1129		tup->tx_dma_chan = NULL;
1130		tup->tx_dma_buf_phys = 0;
1131		tup->tx_dma_buf_virt = NULL;
1132	}
1133}
1134
1135static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup,
1136			bool dma_to_memory)
1137{
1138	struct dma_chan *dma_chan;
1139	unsigned char *dma_buf;
1140	dma_addr_t dma_phys;
1141	int ret;
1142	struct dma_slave_config dma_sconfig;
1143
1144	dma_chan = dma_request_chan(tup->uport.dev, dma_to_memory ? "rx" : "tx");
1145	if (IS_ERR(dma_chan)) {
1146		ret = PTR_ERR(dma_chan);
1147		dev_err(tup->uport.dev,
1148			"DMA channel alloc failed: %d\n", ret);
1149		return ret;
1150	}
1151
1152	if (dma_to_memory) {
1153		dma_buf = dma_alloc_coherent(tup->uport.dev,
1154				TEGRA_UART_RX_DMA_BUFFER_SIZE,
1155				 &dma_phys, GFP_KERNEL);
1156		if (!dma_buf) {
1157			dev_err(tup->uport.dev,
1158				"Not able to allocate the dma buffer\n");
1159			dma_release_channel(dma_chan);
1160			return -ENOMEM;
1161		}
1162		dma_sync_single_for_device(tup->uport.dev, dma_phys,
1163					   TEGRA_UART_RX_DMA_BUFFER_SIZE,
1164					   DMA_TO_DEVICE);
1165		dma_sconfig.src_addr = tup->uport.mapbase;
1166		dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
1167		dma_sconfig.src_maxburst = tup->cdata->max_dma_burst_bytes;
1168		tup->rx_dma_chan = dma_chan;
1169		tup->rx_dma_buf_virt = dma_buf;
1170		tup->rx_dma_buf_phys = dma_phys;
1171	} else {
 
1172		dma_phys = dma_map_single(tup->uport.dev,
1173			tup->uport.state->xmit.buf, UART_XMIT_SIZE,
1174			DMA_TO_DEVICE);
1175		if (dma_mapping_error(tup->uport.dev, dma_phys)) {
1176			dev_err(tup->uport.dev, "dma_map_single tx failed\n");
1177			dma_release_channel(dma_chan);
1178			return -ENOMEM;
1179		}
1180		dma_buf = tup->uport.state->xmit.buf;
1181		dma_sconfig.dst_addr = tup->uport.mapbase;
1182		dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
1183		dma_sconfig.dst_maxburst = 16;
1184		tup->tx_dma_chan = dma_chan;
1185		tup->tx_dma_buf_virt = dma_buf;
1186		tup->tx_dma_buf_phys = dma_phys;
1187	}
1188
1189	ret = dmaengine_slave_config(dma_chan, &dma_sconfig);
1190	if (ret < 0) {
1191		dev_err(tup->uport.dev,
1192			"Dma slave config failed, err = %d\n", ret);
1193		tegra_uart_dma_channel_free(tup, dma_to_memory);
1194		return ret;
1195	}
1196
1197	return 0;
1198}
1199
1200static int tegra_uart_startup(struct uart_port *u)
1201{
1202	struct tegra_uart_port *tup = to_tegra_uport(u);
1203	int ret;
1204
1205	if (!tup->use_tx_pio) {
1206		ret = tegra_uart_dma_channel_allocate(tup, false);
1207		if (ret < 0) {
1208			dev_err(u->dev, "Tx Dma allocation failed, err = %d\n",
1209				ret);
1210			return ret;
1211		}
1212	}
1213
1214	if (!tup->use_rx_pio) {
1215		ret = tegra_uart_dma_channel_allocate(tup, true);
1216		if (ret < 0) {
1217			dev_err(u->dev, "Rx Dma allocation failed, err = %d\n",
1218				ret);
1219			goto fail_rx_dma;
1220		}
1221	}
1222
1223	ret = tegra_uart_hw_init(tup);
1224	if (ret < 0) {
1225		dev_err(u->dev, "Uart HW init failed, err = %d\n", ret);
1226		goto fail_hw_init;
1227	}
1228
1229	ret = request_irq(u->irq, tegra_uart_isr, 0,
1230				dev_name(u->dev), tup);
1231	if (ret < 0) {
1232		dev_err(u->dev, "Failed to register ISR for IRQ %d\n", u->irq);
1233		goto fail_request_irq;
1234	}
1235	return 0;
1236
1237fail_request_irq:
1238	/* tup->uart_clk is already enabled in tegra_uart_hw_init */
1239	clk_disable_unprepare(tup->uart_clk);
1240fail_hw_init:
1241	if (!tup->use_rx_pio)
1242		tegra_uart_dma_channel_free(tup, true);
1243fail_rx_dma:
1244	if (!tup->use_tx_pio)
1245		tegra_uart_dma_channel_free(tup, false);
1246	return ret;
1247}
1248
1249/*
1250 * Flush any TX data submitted for DMA and PIO. Called when the
1251 * TX circular buffer is reset.
1252 */
1253static void tegra_uart_flush_buffer(struct uart_port *u)
1254{
1255	struct tegra_uart_port *tup = to_tegra_uport(u);
1256
1257	tup->tx_bytes = 0;
1258	if (tup->tx_dma_chan)
1259		dmaengine_terminate_all(tup->tx_dma_chan);
1260}
1261
1262static void tegra_uart_shutdown(struct uart_port *u)
1263{
1264	struct tegra_uart_port *tup = to_tegra_uport(u);
1265
1266	tegra_uart_hw_deinit(tup);
1267	free_irq(u->irq, tup);
1268}
1269
1270static void tegra_uart_enable_ms(struct uart_port *u)
1271{
1272	struct tegra_uart_port *tup = to_tegra_uport(u);
1273
1274	if (tup->enable_modem_interrupt) {
1275		tup->ier_shadow |= UART_IER_MSI;
1276		tegra_uart_write(tup, tup->ier_shadow, UART_IER);
1277	}
1278}
1279
1280static void tegra_uart_set_termios(struct uart_port *u,
1281				   struct ktermios *termios,
1282				   const struct ktermios *oldtermios)
1283{
1284	struct tegra_uart_port *tup = to_tegra_uport(u);
1285	unsigned int baud;
1286	unsigned long flags;
1287	unsigned int lcr;
1288	unsigned char char_bits;
1289	struct clk *parent_clk = clk_get_parent(tup->uart_clk);
1290	unsigned long parent_clk_rate = clk_get_rate(parent_clk);
1291	int max_divider = (tup->cdata->support_clk_src_div) ? 0x7FFF : 0xFFFF;
1292	int ret;
1293
1294	max_divider *= 16;
1295	uart_port_lock_irqsave(u, &flags);
1296
1297	/* Changing configuration, it is safe to stop any rx now */
1298	if (tup->rts_active)
1299		set_rts(tup, false);
1300
1301	/* Clear all interrupts as configuration is going to be changed */
1302	tegra_uart_write(tup, tup->ier_shadow | UART_IER_RDI, UART_IER);
1303	tegra_uart_read(tup, UART_IER);
1304	tegra_uart_write(tup, 0, UART_IER);
1305	tegra_uart_read(tup, UART_IER);
1306
1307	/* Parity */
1308	lcr = tup->lcr_shadow;
1309	lcr &= ~UART_LCR_PARITY;
1310
1311	/* CMSPAR isn't supported by this driver */
1312	termios->c_cflag &= ~CMSPAR;
1313
1314	if ((termios->c_cflag & PARENB) == PARENB) {
1315		if (termios->c_cflag & PARODD) {
1316			lcr |= UART_LCR_PARITY;
1317			lcr &= ~UART_LCR_EPAR;
1318			lcr &= ~UART_LCR_SPAR;
1319		} else {
1320			lcr |= UART_LCR_PARITY;
1321			lcr |= UART_LCR_EPAR;
1322			lcr &= ~UART_LCR_SPAR;
1323		}
1324	}
1325
1326	char_bits = tty_get_char_size(termios->c_cflag);
1327	lcr &= ~UART_LCR_WLEN8;
1328	lcr |= UART_LCR_WLEN(char_bits);
1329
1330	/* Stop bits */
1331	if (termios->c_cflag & CSTOPB)
1332		lcr |= UART_LCR_STOP;
1333	else
1334		lcr &= ~UART_LCR_STOP;
1335
1336	tegra_uart_write(tup, lcr, UART_LCR);
1337	tup->lcr_shadow = lcr;
1338	tup->symb_bit = tty_get_frame_size(termios->c_cflag);
1339
1340	/* Baud rate. */
1341	baud = uart_get_baud_rate(u, termios, oldtermios,
1342			parent_clk_rate/max_divider,
1343			parent_clk_rate/16);
1344	uart_port_unlock_irqrestore(u, flags);
1345	ret = tegra_set_baudrate(tup, baud);
1346	if (ret < 0) {
1347		dev_err(tup->uport.dev, "Failed to set baud rate\n");
1348		return;
1349	}
1350	if (tty_termios_baud_rate(termios))
1351		tty_termios_encode_baud_rate(termios, baud, baud);
1352	uart_port_lock_irqsave(u, &flags);
1353
1354	/* Flow control */
1355	if (termios->c_cflag & CRTSCTS)	{
1356		tup->mcr_shadow |= TEGRA_UART_MCR_CTS_EN;
1357		tup->mcr_shadow &= ~TEGRA_UART_MCR_RTS_EN;
1358		tegra_uart_write(tup, tup->mcr_shadow, UART_MCR);
1359		/* if top layer has asked to set rts active then do so here */
1360		if (tup->rts_active)
1361			set_rts(tup, true);
1362	} else {
1363		tup->mcr_shadow &= ~TEGRA_UART_MCR_CTS_EN;
1364		tup->mcr_shadow &= ~TEGRA_UART_MCR_RTS_EN;
1365		tegra_uart_write(tup, tup->mcr_shadow, UART_MCR);
1366	}
1367
1368	/* update the port timeout based on new settings */
1369	uart_update_timeout(u, termios->c_cflag, baud);
1370
1371	/* Make sure all writes have completed */
1372	tegra_uart_read(tup, UART_IER);
1373
1374	/* Re-enable interrupt */
1375	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
1376	tegra_uart_read(tup, UART_IER);
1377
1378	tup->uport.ignore_status_mask = 0;
1379	/* Ignore all characters if CREAD is not set */
1380	if ((termios->c_cflag & CREAD) == 0)
1381		tup->uport.ignore_status_mask |= UART_LSR_DR;
1382	if (termios->c_iflag & IGNBRK)
1383		tup->uport.ignore_status_mask |= UART_LSR_BI;
1384
1385	uart_port_unlock_irqrestore(u, flags);
1386}
1387
1388static const char *tegra_uart_type(struct uart_port *u)
1389{
1390	return TEGRA_UART_TYPE;
1391}
1392
1393static const struct uart_ops tegra_uart_ops = {
1394	.tx_empty	= tegra_uart_tx_empty,
1395	.set_mctrl	= tegra_uart_set_mctrl,
1396	.get_mctrl	= tegra_uart_get_mctrl,
1397	.stop_tx	= tegra_uart_stop_tx,
1398	.start_tx	= tegra_uart_start_tx,
1399	.stop_rx	= tegra_uart_stop_rx,
1400	.flush_buffer	= tegra_uart_flush_buffer,
1401	.enable_ms	= tegra_uart_enable_ms,
1402	.break_ctl	= tegra_uart_break_ctl,
1403	.startup	= tegra_uart_startup,
1404	.shutdown	= tegra_uart_shutdown,
1405	.set_termios	= tegra_uart_set_termios,
1406	.type		= tegra_uart_type,
1407	.request_port	= tegra_uart_request_port,
1408	.release_port	= tegra_uart_release_port,
1409};
1410
1411static struct uart_driver tegra_uart_driver = {
1412	.owner		= THIS_MODULE,
1413	.driver_name	= "tegra_hsuart",
1414	.dev_name	= "ttyTHS",
1415	.cons		= NULL,
1416	.nr		= TEGRA_UART_MAXIMUM,
1417};
1418
1419static int tegra_uart_parse_dt(struct platform_device *pdev,
1420	struct tegra_uart_port *tup)
1421{
1422	struct device_node *np = pdev->dev.of_node;
1423	int port;
1424	int ret;
1425	int index;
1426	u32 pval;
1427	int count;
1428	int n_entries;
1429
1430	port = of_alias_get_id(np, "serial");
1431	if (port < 0) {
1432		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", port);
1433		return port;
1434	}
1435	tup->uport.line = port;
1436
1437	tup->enable_modem_interrupt = of_property_read_bool(np,
1438					"nvidia,enable-modem-interrupt");
1439
1440	index = of_property_match_string(np, "dma-names", "rx");
1441	if (index < 0) {
1442		tup->use_rx_pio = true;
1443		dev_info(&pdev->dev, "RX in PIO mode\n");
1444	}
1445	index = of_property_match_string(np, "dma-names", "tx");
1446	if (index < 0) {
1447		tup->use_tx_pio = true;
1448		dev_info(&pdev->dev, "TX in PIO mode\n");
1449	}
1450
1451	n_entries = of_property_count_u32_elems(np, "nvidia,adjust-baud-rates");
1452	if (n_entries > 0) {
1453		tup->n_adjustable_baud_rates = n_entries / 3;
1454		tup->baud_tolerance =
1455		devm_kzalloc(&pdev->dev, (tup->n_adjustable_baud_rates) *
1456			     sizeof(*tup->baud_tolerance), GFP_KERNEL);
1457		if (!tup->baud_tolerance)
1458			return -ENOMEM;
1459		for (count = 0, index = 0; count < n_entries; count += 3,
1460		     index++) {
1461			ret =
1462			of_property_read_u32_index(np,
1463						   "nvidia,adjust-baud-rates",
1464						   count, &pval);
1465			if (!ret)
1466				tup->baud_tolerance[index].lower_range_baud =
1467				pval;
1468			ret =
1469			of_property_read_u32_index(np,
1470						   "nvidia,adjust-baud-rates",
1471						   count + 1, &pval);
1472			if (!ret)
1473				tup->baud_tolerance[index].upper_range_baud =
1474				pval;
1475			ret =
1476			of_property_read_u32_index(np,
1477						   "nvidia,adjust-baud-rates",
1478						   count + 2, &pval);
1479			if (!ret)
1480				tup->baud_tolerance[index].tolerance =
1481				(s32)pval;
1482		}
1483	} else {
1484		tup->n_adjustable_baud_rates = 0;
1485	}
1486
1487	return 0;
1488}
1489
1490static struct tegra_uart_chip_data tegra20_uart_chip_data = {
1491	.tx_fifo_full_status		= false,
1492	.allow_txfifo_reset_fifo_mode	= true,
1493	.support_clk_src_div		= false,
1494	.fifo_mode_enable_status	= false,
1495	.uart_max_port			= 5,
1496	.max_dma_burst_bytes		= 4,
1497	.error_tolerance_low_range	= -4,
1498	.error_tolerance_high_range	= 4,
1499};
1500
1501static struct tegra_uart_chip_data tegra30_uart_chip_data = {
1502	.tx_fifo_full_status		= true,
1503	.allow_txfifo_reset_fifo_mode	= false,
1504	.support_clk_src_div		= true,
1505	.fifo_mode_enable_status	= false,
1506	.uart_max_port			= 5,
1507	.max_dma_burst_bytes		= 4,
1508	.error_tolerance_low_range	= -4,
1509	.error_tolerance_high_range	= 4,
1510};
1511
1512static struct tegra_uart_chip_data tegra186_uart_chip_data = {
1513	.tx_fifo_full_status		= true,
1514	.allow_txfifo_reset_fifo_mode	= false,
1515	.support_clk_src_div		= true,
1516	.fifo_mode_enable_status	= true,
1517	.uart_max_port			= 8,
1518	.max_dma_burst_bytes		= 8,
1519	.error_tolerance_low_range	= 0,
1520	.error_tolerance_high_range	= 4,
1521};
1522
1523static struct tegra_uart_chip_data tegra194_uart_chip_data = {
1524	.tx_fifo_full_status		= true,
1525	.allow_txfifo_reset_fifo_mode	= false,
1526	.support_clk_src_div		= true,
1527	.fifo_mode_enable_status	= true,
1528	.uart_max_port			= 8,
1529	.max_dma_burst_bytes		= 8,
1530	.error_tolerance_low_range	= -2,
1531	.error_tolerance_high_range	= 2,
1532};
1533
1534static const struct of_device_id tegra_uart_of_match[] = {
1535	{
1536		.compatible	= "nvidia,tegra30-hsuart",
1537		.data		= &tegra30_uart_chip_data,
1538	}, {
1539		.compatible	= "nvidia,tegra20-hsuart",
1540		.data		= &tegra20_uart_chip_data,
1541	}, {
1542		.compatible     = "nvidia,tegra186-hsuart",
1543		.data		= &tegra186_uart_chip_data,
1544	}, {
1545		.compatible     = "nvidia,tegra194-hsuart",
1546		.data		= &tegra194_uart_chip_data,
1547	}, {
1548	},
1549};
1550MODULE_DEVICE_TABLE(of, tegra_uart_of_match);
1551
1552static int tegra_uart_probe(struct platform_device *pdev)
1553{
1554	struct tegra_uart_port *tup;
1555	struct uart_port *u;
1556	struct resource *resource;
1557	int ret;
1558	const struct tegra_uart_chip_data *cdata;
1559
1560	cdata = of_device_get_match_data(&pdev->dev);
1561	if (!cdata) {
1562		dev_err(&pdev->dev, "Error: No device match found\n");
1563		return -ENODEV;
1564	}
1565
1566	tup = devm_kzalloc(&pdev->dev, sizeof(*tup), GFP_KERNEL);
1567	if (!tup) {
1568		dev_err(&pdev->dev, "Failed to allocate memory for tup\n");
1569		return -ENOMEM;
1570	}
1571
1572	ret = tegra_uart_parse_dt(pdev, tup);
1573	if (ret < 0)
1574		return ret;
1575
1576	u = &tup->uport;
1577	u->dev = &pdev->dev;
1578	u->ops = &tegra_uart_ops;
1579	u->type = PORT_TEGRA;
1580	u->fifosize = 32;
1581	tup->cdata = cdata;
1582
1583	platform_set_drvdata(pdev, tup);
1584
1585	u->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &resource);
1586	if (IS_ERR(u->membase))
1587		return PTR_ERR(u->membase);
1588	u->mapbase = resource->start;
1589
1590	tup->uart_clk = devm_clk_get(&pdev->dev, NULL);
1591	if (IS_ERR(tup->uart_clk))
1592		return dev_err_probe(&pdev->dev, PTR_ERR(tup->uart_clk), "Couldn't get the clock");
1593
1594	tup->rst = devm_reset_control_get_exclusive(&pdev->dev, "serial");
1595	if (IS_ERR(tup->rst)) {
1596		dev_err(&pdev->dev, "Couldn't get the reset\n");
1597		return PTR_ERR(tup->rst);
1598	}
1599
1600	u->iotype = UPIO_MEM32;
1601	ret = platform_get_irq(pdev, 0);
1602	if (ret < 0)
1603		return ret;
1604	u->irq = ret;
1605	u->regshift = 2;
1606	ret = uart_add_one_port(&tegra_uart_driver, u);
1607	if (ret < 0) {
1608		dev_err(&pdev->dev, "Failed to add uart port, err %d\n", ret);
1609		return ret;
1610	}
1611	return ret;
1612}
1613
1614static void tegra_uart_remove(struct platform_device *pdev)
1615{
1616	struct tegra_uart_port *tup = platform_get_drvdata(pdev);
1617	struct uart_port *u = &tup->uport;
1618
1619	uart_remove_one_port(&tegra_uart_driver, u);
1620}
1621
1622#ifdef CONFIG_PM_SLEEP
1623static int tegra_uart_suspend(struct device *dev)
1624{
1625	struct tegra_uart_port *tup = dev_get_drvdata(dev);
1626	struct uart_port *u = &tup->uport;
1627
1628	return uart_suspend_port(&tegra_uart_driver, u);
1629}
1630
1631static int tegra_uart_resume(struct device *dev)
1632{
1633	struct tegra_uart_port *tup = dev_get_drvdata(dev);
1634	struct uart_port *u = &tup->uport;
1635
1636	return uart_resume_port(&tegra_uart_driver, u);
1637}
1638#endif
1639
1640static const struct dev_pm_ops tegra_uart_pm_ops = {
1641	SET_SYSTEM_SLEEP_PM_OPS(tegra_uart_suspend, tegra_uart_resume)
1642};
1643
1644static struct platform_driver tegra_uart_platform_driver = {
1645	.probe		= tegra_uart_probe,
1646	.remove_new	= tegra_uart_remove,
1647	.driver		= {
1648		.name	= "serial-tegra",
1649		.of_match_table = tegra_uart_of_match,
1650		.pm	= &tegra_uart_pm_ops,
1651	},
1652};
1653
1654static int __init tegra_uart_init(void)
1655{
1656	int ret;
1657	struct device_node *node;
1658	const struct of_device_id *match = NULL;
1659	const struct tegra_uart_chip_data *cdata = NULL;
1660
1661	node = of_find_matching_node(NULL, tegra_uart_of_match);
1662	if (node)
1663		match = of_match_node(tegra_uart_of_match, node);
1664	of_node_put(node);
1665	if (match)
1666		cdata = match->data;
1667	if (cdata)
1668		tegra_uart_driver.nr = cdata->uart_max_port;
1669
1670	ret = uart_register_driver(&tegra_uart_driver);
1671	if (ret < 0) {
1672		pr_err("Could not register %s driver\n",
1673		       tegra_uart_driver.driver_name);
1674		return ret;
1675	}
1676
1677	ret = platform_driver_register(&tegra_uart_platform_driver);
1678	if (ret < 0) {
1679		pr_err("Uart platform driver register failed, e = %d\n", ret);
1680		uart_unregister_driver(&tegra_uart_driver);
1681		return ret;
1682	}
1683	return 0;
1684}
1685
1686static void __exit tegra_uart_exit(void)
1687{
1688	pr_info("Unloading tegra uart driver\n");
1689	platform_driver_unregister(&tegra_uart_platform_driver);
1690	uart_unregister_driver(&tegra_uart_driver);
1691}
1692
1693module_init(tegra_uart_init);
1694module_exit(tegra_uart_exit);
1695
1696MODULE_ALIAS("platform:serial-tegra");
1697MODULE_DESCRIPTION("High speed UART driver for tegra chipset");
1698MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
1699MODULE_LICENSE("GPL v2");