1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Altera SPI driver
  4 *
  5 * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
  6 *
  7 * Based on spi_s3c24xx.c, which is:
  8 * Copyright (c) 2006 Ben Dooks
  9 * Copyright (c) 2006 Simtec Electronics
 10 *	Ben Dooks <ben@simtec.co.uk>
 11 */
 12
 13#include <linux/interrupt.h>
 14#include <linux/errno.h>
 15#include <linux/module.h>
 16#include <linux/platform_device.h>
 17#include <linux/spi/spi.h>
 18#include <linux/io.h>
 19#include <linux/of.h>
 20
 21#define DRV_NAME "spi_altera"
 22
 23#define ALTERA_SPI_RXDATA	0
 24#define ALTERA_SPI_TXDATA	4
 25#define ALTERA_SPI_STATUS	8
 26#define ALTERA_SPI_CONTROL	12
 27#define ALTERA_SPI_SLAVE_SEL	20
 28
 29#define ALTERA_SPI_STATUS_ROE_MSK	0x8
 30#define ALTERA_SPI_STATUS_TOE_MSK	0x10
 31#define ALTERA_SPI_STATUS_TMT_MSK	0x20
 32#define ALTERA_SPI_STATUS_TRDY_MSK	0x40
 33#define ALTERA_SPI_STATUS_RRDY_MSK	0x80
 34#define ALTERA_SPI_STATUS_E_MSK		0x100
 35
 36#define ALTERA_SPI_CONTROL_IROE_MSK	0x8
 37#define ALTERA_SPI_CONTROL_ITOE_MSK	0x10
 38#define ALTERA_SPI_CONTROL_ITRDY_MSK	0x40
 39#define ALTERA_SPI_CONTROL_IRRDY_MSK	0x80
 40#define ALTERA_SPI_CONTROL_IE_MSK	0x100
 41#define ALTERA_SPI_CONTROL_SSO_MSK	0x400
 42
 43struct altera_spi {
 44	void __iomem *base;
 45	int irq;
 46	int len;
 47	int count;
 48	int bytes_per_word;
 49	unsigned long imr;
 50
 51	/* data buffers */
 52	const unsigned char *tx;
 53	unsigned char *rx;
 54};
 55
 56static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
 57{
 58	return spi_master_get_devdata(sdev->master);
 59}
 60
 61static void altera_spi_set_cs(struct spi_device *spi, bool is_high)
 62{
 63	struct altera_spi *hw = altera_spi_to_hw(spi);
 64
 65	if (is_high) {
 66		hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
 67		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 68		writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
 69	} else {
 70		writel(BIT(spi->chip_select), hw->base + ALTERA_SPI_SLAVE_SEL);
 71		hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
 72		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 73	}
 74}
 75
 76static void altera_spi_tx_word(struct altera_spi *hw)
 77{
 78	unsigned int txd = 0;
 79
 80	if (hw->tx) {
 81		switch (hw->bytes_per_word) {
 82		case 1:
 83			txd = hw->tx[hw->count];
 84			break;
 85		case 2:
 86			txd = (hw->tx[hw->count * 2]
 87				| (hw->tx[hw->count * 2 + 1] << 8));
 88			break;
 89		}
 90	}
 91
 92	writel(txd, hw->base + ALTERA_SPI_TXDATA);
 93}
 94
 95static void altera_spi_rx_word(struct altera_spi *hw)
 96{
 97	unsigned int rxd;
 98
 99	rxd = readl(hw->base + ALTERA_SPI_RXDATA);
100	if (hw->rx) {
101		switch (hw->bytes_per_word) {
102		case 1:
103			hw->rx[hw->count] = rxd;
104			break;
105		case 2:
106			hw->rx[hw->count * 2] = rxd;
107			hw->rx[hw->count * 2 + 1] = rxd >> 8;
108			break;
109		}
110	}
111
112	hw->count++;
113}
114
115static int altera_spi_txrx(struct spi_master *master,
116	struct spi_device *spi, struct spi_transfer *t)
117{
118	struct altera_spi *hw = spi_master_get_devdata(master);
119
120	hw->tx = t->tx_buf;
121	hw->rx = t->rx_buf;
122	hw->count = 0;
123	hw->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
124	hw->len = t->len / hw->bytes_per_word;
125
126	if (hw->irq >= 0) {
127		/* enable receive interrupt */
128		hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
129		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
130
131		/* send the first byte */
132		altera_spi_tx_word(hw);
133	} else {
134		while (hw->count < hw->len) {
135			altera_spi_tx_word(hw);
136
137			while (!(readl(hw->base + ALTERA_SPI_STATUS) &
138				 ALTERA_SPI_STATUS_RRDY_MSK))
139				cpu_relax();
140
141			altera_spi_rx_word(hw);
142		}
143		spi_finalize_current_transfer(master);
144	}
145
146	return t->len;
147}
148
149static irqreturn_t altera_spi_irq(int irq, void *dev)
150{
151	struct spi_master *master = dev;
152	struct altera_spi *hw = spi_master_get_devdata(master);
153
154	altera_spi_rx_word(hw);
155
156	if (hw->count < hw->len) {
157		altera_spi_tx_word(hw);
158	} else {
159		/* disable receive interrupt */
160		hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
161		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
162
163		spi_finalize_current_transfer(master);
164	}
165
166	return IRQ_HANDLED;
167}
168
169static int altera_spi_probe(struct platform_device *pdev)
170{
171	struct altera_spi *hw;
172	struct spi_master *master;
173	int err = -ENODEV;
174
175	master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
176	if (!master)
177		return err;
178
179	/* setup the master state. */
180	master->bus_num = pdev->id;
181	master->num_chipselect = 16;
182	master->mode_bits = SPI_CS_HIGH;
183	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
184	master->dev.of_node = pdev->dev.of_node;
185	master->transfer_one = altera_spi_txrx;
186	master->set_cs = altera_spi_set_cs;
187
188	hw = spi_master_get_devdata(master);
189
190	/* find and map our resources */
191	hw->base = devm_platform_ioremap_resource(pdev, 0);
192	if (IS_ERR(hw->base)) {
193		err = PTR_ERR(hw->base);
194		goto exit;
195	}
196	/* program defaults into the registers */
197	hw->imr = 0;		/* disable spi interrupts */
198	writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
199	writel(0, hw->base + ALTERA_SPI_STATUS);	/* clear status reg */
200	if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
201		readl(hw->base + ALTERA_SPI_RXDATA);	/* flush rxdata */
202	/* irq is optional */
203	hw->irq = platform_get_irq(pdev, 0);
204	if (hw->irq >= 0) {
205		err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
206				       pdev->name, master);
207		if (err)
208			goto exit;
209	}
210
211	err = devm_spi_register_master(&pdev->dev, master);
212	if (err)
213		goto exit;
214	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
215
216	return 0;
217exit:
218	spi_master_put(master);
219	return err;
220}
221
222#ifdef CONFIG_OF
223static const struct of_device_id altera_spi_match[] = {
224	{ .compatible = "ALTR,spi-1.0", },
225	{ .compatible = "altr,spi-1.0", },
226	{},
227};
228MODULE_DEVICE_TABLE(of, altera_spi_match);
229#endif /* CONFIG_OF */
230
231static struct platform_driver altera_spi_driver = {
232	.probe = altera_spi_probe,
233	.driver = {
234		.name = DRV_NAME,
235		.pm = NULL,
236		.of_match_table = of_match_ptr(altera_spi_match),
237	},
238};
239module_platform_driver(altera_spi_driver);
240
241MODULE_DESCRIPTION("Altera SPI driver");
242MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
243MODULE_LICENSE("GPL");
244MODULE_ALIAS("platform:" DRV_NAME);