1/*
  2 *  CLPS711X SPI bus driver
  3 *
  4 *  Copyright (C) 2012-2016 Alexander Shiyan <shc_work@mail.ru>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; either version 2 of the License, or
  9 * (at your option) any later version.
 10 */
 11
 12#include <linux/io.h>
 13#include <linux/clk.h>
 14#include <linux/gpio.h>
 15#include <linux/module.h>
 16#include <linux/interrupt.h>
 17#include <linux/platform_device.h>
 18#include <linux/regmap.h>
 19#include <linux/mfd/syscon.h>
 20#include <linux/mfd/syscon/clps711x.h>
 21#include <linux/spi/spi.h>
 22
 23#define DRIVER_NAME		"clps711x-spi"
 24
 25#define SYNCIO_FRMLEN(x)	((x) << 8)
 26#define SYNCIO_TXFRMEN		(1 << 14)
 27
 28struct spi_clps711x_data {
 29	void __iomem		*syncio;
 30	struct regmap		*syscon;
 31	struct clk		*spi_clk;
 32
 33	u8			*tx_buf;
 34	u8			*rx_buf;
 35	unsigned int		bpw;
 36	int			len;
 37};
 38
 39static int spi_clps711x_setup(struct spi_device *spi)
 40{
 41	if (!spi->controller_state) {
 42		int ret;
 43
 44		ret = devm_gpio_request(&spi->master->dev, spi->cs_gpio,
 45					dev_name(&spi->master->dev));
 46		if (ret)
 47			return ret;
 48
 49		spi->controller_state = spi;
 50	}
 51
 52	/* We are expect that SPI-device is not selected */
 53	gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
 54
 55	return 0;
 56}
 57
 58static int spi_clps711x_prepare_message(struct spi_master *master,
 59					struct spi_message *msg)
 60{
 61	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 62	struct spi_device *spi = msg->spi;
 63
 64	/* Setup mode for transfer */
 65	return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
 66				  (spi->mode & SPI_CPHA) ?
 67				  SYSCON3_ADCCKNSEN : 0);
 68}
 69
 70static int spi_clps711x_transfer_one(struct spi_master *master,
 71				     struct spi_device *spi,
 72				     struct spi_transfer *xfer)
 73{
 74	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 75	u8 data;
 76
 77	clk_set_rate(hw->spi_clk, xfer->speed_hz ? : spi->max_speed_hz);
 78
 79	hw->len = xfer->len;
 80	hw->bpw = xfer->bits_per_word;
 81	hw->tx_buf = (u8 *)xfer->tx_buf;
 82	hw->rx_buf = (u8 *)xfer->rx_buf;
 83
 84	/* Initiate transfer */
 85	data = hw->tx_buf ? *hw->tx_buf++ : 0;
 86	writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
 87
 88	return 1;
 89}
 90
 91static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
 92{
 93	struct spi_master *master = dev_id;
 94	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
 95	u8 data;
 96
 97	/* Handle RX */
 98	data = readb(hw->syncio);
 99	if (hw->rx_buf)
100		*hw->rx_buf++ = data;
101
102	/* Handle TX */
103	if (--hw->len > 0) {
104		data = hw->tx_buf ? *hw->tx_buf++ : 0;
105		writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
106		       hw->syncio);
107	} else
108		spi_finalize_current_transfer(master);
109
110	return IRQ_HANDLED;
111}
112
113static int spi_clps711x_probe(struct platform_device *pdev)
114{
115	struct spi_clps711x_data *hw;
116	struct spi_master *master;
117	struct resource *res;
118	int irq, ret;
119
120	irq = platform_get_irq(pdev, 0);
121	if (irq < 0)
122		return irq;
123
124	master = spi_alloc_master(&pdev->dev, sizeof(*hw));
125	if (!master)
126		return -ENOMEM;
127
128	master->bus_num = -1;
129	master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
130	master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
131	master->dev.of_node = pdev->dev.of_node;
132	master->setup = spi_clps711x_setup;
133	master->prepare_message = spi_clps711x_prepare_message;
134	master->transfer_one = spi_clps711x_transfer_one;
135
136	hw = spi_master_get_devdata(master);
137
138	hw->spi_clk = devm_clk_get(&pdev->dev, NULL);
139	if (IS_ERR(hw->spi_clk)) {
140		ret = PTR_ERR(hw->spi_clk);
141		goto err_out;
142	}
143
144	hw->syscon =
145		syscon_regmap_lookup_by_compatible("cirrus,ep7209-syscon3");
146	if (IS_ERR(hw->syscon)) {
147		ret = PTR_ERR(hw->syscon);
148		goto err_out;
149	}
150
151	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
152	hw->syncio = devm_ioremap_resource(&pdev->dev, res);
153	if (IS_ERR(hw->syncio)) {
154		ret = PTR_ERR(hw->syncio);
155		goto err_out;
156	}
157
158	/* Disable extended mode due hardware problems */
159	regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
160
161	/* Clear possible pending interrupt */
162	readl(hw->syncio);
163
164	ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
165			       dev_name(&pdev->dev), master);
166	if (ret)
167		goto err_out;
168
169	ret = devm_spi_register_master(&pdev->dev, master);
170	if (!ret)
171		return 0;
172
173err_out:
174	spi_master_put(master);
175
176	return ret;
177}
178
179static const struct of_device_id clps711x_spi_dt_ids[] = {
180	{ .compatible = "cirrus,ep7209-spi", },
181	{ }
182};
183MODULE_DEVICE_TABLE(of, clps711x_spi_dt_ids);
184
185static struct platform_driver clps711x_spi_driver = {
186	.driver	= {
187		.name	= DRIVER_NAME,
188		.of_match_table = clps711x_spi_dt_ids,
189	},
190	.probe	= spi_clps711x_probe,
191};
192module_platform_driver(clps711x_spi_driver);
193
194MODULE_LICENSE("GPL");
195MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
196MODULE_DESCRIPTION("CLPS711X SPI bus driver");
197MODULE_ALIAS("platform:" DRIVER_NAME);