1/*
2 *  CLPS711X SPI bus driver
3 *
4 *  Copyright (C) 2012-2014 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/delay.h>
16#include <linux/module.h>
17#include <linux/interrupt.h>
18#include <linux/platform_device.h>
19#include <linux/regmap.h>
20#include <linux/mfd/syscon.h>
21#include <linux/mfd/syscon/clps711x.h>
22#include <linux/spi/spi.h>
23#include <linux/platform_data/spi-clps711x.h>
24
25#define DRIVER_NAME	"spi-clps711x"
26
27#define SYNCIO_FRMLEN(x)	((x) << 8)
28#define SYNCIO_TXFRMEN		(1 << 14)
29
30struct spi_clps711x_data {
31	void __iomem		*syncio;
32	struct regmap		*syscon;
33	struct clk		*spi_clk;
34
35	u8			*tx_buf;
36	u8			*rx_buf;
37	unsigned int		bpw;
38	int			len;
39};
40
41static int spi_clps711x_setup(struct spi_device *spi)
42{
43	/* We are expect that SPI-device is not selected */
44	gpio_direction_output(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
45
46	return 0;
47}
48
49static int spi_clps711x_prepare_message(struct spi_master *master,
50					struct spi_message *msg)
51{
52	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
53	struct spi_device *spi = msg->spi;
54
55	/* Setup mode for transfer */
56	return regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCKNSEN,
57				  (spi->mode & SPI_CPHA) ?
58				  SYSCON3_ADCCKNSEN : 0);
59}
60
61static int spi_clps711x_transfer_one(struct spi_master *master,
62				     struct spi_device *spi,
63				     struct spi_transfer *xfer)
64{
65	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
66	u8 data;
67
68	clk_set_rate(hw->spi_clk, xfer->speed_hz ? : spi->max_speed_hz);
69
70	hw->len = xfer->len;
71	hw->bpw = xfer->bits_per_word;
72	hw->tx_buf = (u8 *)xfer->tx_buf;
73	hw->rx_buf = (u8 *)xfer->rx_buf;
74
75	/* Initiate transfer */
76	data = hw->tx_buf ? *hw->tx_buf++ : 0;
77	writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN, hw->syncio);
78
79	return 1;
80}
81
82static irqreturn_t spi_clps711x_isr(int irq, void *dev_id)
83{
84	struct spi_master *master = dev_id;
85	struct spi_clps711x_data *hw = spi_master_get_devdata(master);
86	u8 data;
87
88	/* Handle RX */
89	data = readb(hw->syncio);
90	if (hw->rx_buf)
91		*hw->rx_buf++ = data;
92
93	/* Handle TX */
94	if (--hw->len > 0) {
95		data = hw->tx_buf ? *hw->tx_buf++ : 0;
96		writel(data | SYNCIO_FRMLEN(hw->bpw) | SYNCIO_TXFRMEN,
97		       hw->syncio);
98	} else
99		spi_finalize_current_transfer(master);
100
101	return IRQ_HANDLED;
102}
103
104static int spi_clps711x_probe(struct platform_device *pdev)
105{
106	struct spi_clps711x_data *hw;
107	struct spi_clps711x_pdata *pdata = dev_get_platdata(&pdev->dev);
108	struct spi_master *master;
109	struct resource *res;
110	int i, irq, ret;
111
112	if (!pdata) {
113		dev_err(&pdev->dev, "No platform data supplied\n");
114		return -EINVAL;
115	}
116
117	if (pdata->num_chipselect < 1) {
118		dev_err(&pdev->dev, "At least one CS must be defined\n");
119		return -EINVAL;
120	}
121
122	irq = platform_get_irq(pdev, 0);
123	if (irq < 0)
124		return irq;
125
126	master = spi_alloc_master(&pdev->dev, sizeof(*hw));
127	if (!master)
128		return -ENOMEM;
129
130	master->cs_gpios = devm_kzalloc(&pdev->dev, sizeof(int) *
131					pdata->num_chipselect, GFP_KERNEL);
132	if (!master->cs_gpios) {
133		ret = -ENOMEM;
134		goto err_out;
135	}
136
137	master->bus_num = pdev->id;
138	master->mode_bits = SPI_CPHA | SPI_CS_HIGH;
139	master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(1, 8);
140	master->num_chipselect = pdata->num_chipselect;
141	master->setup = spi_clps711x_setup;
142	master->prepare_message = spi_clps711x_prepare_message;
143	master->transfer_one = spi_clps711x_transfer_one;
144
145	hw = spi_master_get_devdata(master);
146
147	for (i = 0; i < master->num_chipselect; i++) {
148		master->cs_gpios[i] = pdata->chipselect[i];
149		ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
150					DRIVER_NAME);
151		if (ret) {
152			dev_err(&pdev->dev, "Can't get CS GPIO %i\n", i);
153			goto err_out;
154		}
155	}
156
157	hw->spi_clk = devm_clk_get(&pdev->dev, NULL);
158	if (IS_ERR(hw->spi_clk)) {
159		ret = PTR_ERR(hw->spi_clk);
160		goto err_out;
161	}
162
163	hw->syscon = syscon_regmap_lookup_by_pdevname("syscon.3");
164	if (IS_ERR(hw->syscon)) {
165		ret = PTR_ERR(hw->syscon);
166		goto err_out;
167	}
168
169	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
170	hw->syncio = devm_ioremap_resource(&pdev->dev, res);
171	if (IS_ERR(hw->syncio)) {
172		ret = PTR_ERR(hw->syncio);
173		goto err_out;
174	}
175
176	/* Disable extended mode due hardware problems */
177	regmap_update_bits(hw->syscon, SYSCON_OFFSET, SYSCON3_ADCCON, 0);
178
179	/* Clear possible pending interrupt */
180	readl(hw->syncio);
181
182	ret = devm_request_irq(&pdev->dev, irq, spi_clps711x_isr, 0,
183			       dev_name(&pdev->dev), master);
184	if (ret)
185		goto err_out;
186
187	ret = devm_spi_register_master(&pdev->dev, master);
188	if (!ret) {
189		dev_info(&pdev->dev,
190			 "SPI bus driver initialized. Master clock %u Hz\n",
191			 master->max_speed_hz);
192		return 0;
193	}
194
195	dev_err(&pdev->dev, "Failed to register master\n");
196
197err_out:
198	spi_master_put(master);
199
200	return ret;
201}
202
203static struct platform_driver clps711x_spi_driver = {
204	.driver	= {
205		.name	= DRIVER_NAME,
206	},
207	.probe	= spi_clps711x_probe,
208};
209module_platform_driver(clps711x_spi_driver);
210
211MODULE_LICENSE("GPL");
212MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
213MODULE_DESCRIPTION("CLPS711X SPI bus driver");
214MODULE_ALIAS("platform:" DRIVER_NAME);
215