summaryrefslogtreecommitdiffstats
path: root/drivers/spi/spi-ath79.c
blob: d4b8e1236612e192576ff44f6d941bbc553b3ecd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
/*
 * SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
 *
 * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
 *
 * This driver has been based on the spi-gpio.c:
 *	Copyright (C) 2006,2008 David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/bitops.h>
#include <linux/gpio.h>
#include <linux/clk.h>
#include <linux/err.h>

#include <asm/mach-ath79/ar71xx_regs.h>
#include <asm/mach-ath79/ath79_spi_platform.h>

#define DRV_NAME	"ath79-spi"

#define ATH79_SPI_RRW_DELAY_FACTOR	12000
#define MHZ				(1000 * 1000)

struct ath79_spi {
	struct spi_bitbang	bitbang;
	u32			ioc_base;
	u32			reg_ctrl;
	void __iomem		*base;
	struct clk		*clk;
	unsigned		rrw_delay;
};

static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
{
	return ioread32(sp->base + reg);
}

static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned reg, u32 val)
{
	iowrite32(val, sp->base + reg);
}

static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
{
	return spi_master_get_devdata(spi->master);
}

static inline void ath79_spi_delay(struct ath79_spi *sp, unsigned nsecs)
{
	if (nsecs > sp->rrw_delay)
		ndelay(nsecs - sp->rrw_delay);
}

static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
{
	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
	int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;

	if (is_active) {
		/* set initial clock polarity */
		if (spi->mode & SPI_CPOL)
			sp->ioc_base |= AR71XX_SPI_IOC_CLK;
		else
			sp->ioc_base &= ~AR71XX_SPI_IOC_CLK;

		ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
	}

	if (spi->chip_select) {
		struct ath79_spi_controller_data *cdata = spi->controller_data;

		/* SPI is normally active-low */
		gpio_set_value(cdata->gpio, cs_high);
	} else {
		if (cs_high)
			sp->ioc_base |= AR71XX_SPI_IOC_CS0;
		else
			sp->ioc_base &= ~AR71XX_SPI_IOC_CS0;

		ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
	}

}

static int ath79_spi_setup_cs(struct spi_device *spi)
{
	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
	struct ath79_spi_controller_data *cdata;

	cdata = spi->controller_data;
	if (spi->chip_select && !cdata)
		return -EINVAL;

	/* enable GPIO mode */
	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);

	/* save CTRL register */
	sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
	sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);

	/* TODO: setup speed? */
	ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);

	if (spi->chip_select) {
		int status = 0;

		status = gpio_request(cdata->gpio, dev_name(&spi->dev));
		if (status)
			return status;

		status = gpio_direction_output(cdata->gpio,
					       spi->mode & SPI_CS_HIGH);
		if (status) {
			gpio_free(cdata->gpio);
			return status;
		}
	} else {
		if (spi->mode & SPI_CS_HIGH)
			sp->ioc_base |= AR71XX_SPI_IOC_CS0;
		else
			sp->ioc_base &= ~AR71XX_SPI_IOC_CS0;
		ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
	}

	return 0;
}

static void ath79_spi_cleanup_cs(struct spi_device *spi)
{
	struct ath79_spi *sp = ath79_spidev_to_sp(spi);

	if (spi->chip_select) {
		struct ath79_spi_controller_data *cdata = spi->controller_data;
		gpio_free(cdata->gpio);
	}

	/* restore CTRL register */
	ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
	/* disable GPIO mode */
	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
}

static int ath79_spi_setup(struct spi_device *spi)
{
	int status = 0;

	if (spi->bits_per_word > 32)
		return -EINVAL;

	if (!spi->controller_state) {
		status = ath79_spi_setup_cs(spi);
		if (status)
			return status;
	}

	status = spi_bitbang_setup(spi);
	if (status && !spi->controller_state)
		ath79_spi_cleanup_cs(spi);

	return status;
}

static void ath79_spi_cleanup(struct spi_device *spi)
{
	ath79_spi_cleanup_cs(spi);
	spi_bitbang_cleanup(spi);
}

static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
			       u32 word, u8 bits)
{
	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
	u32 ioc = sp->ioc_base;

	/* clock starts at inactive polarity */
	for (word <<= (32 - bits); likely(bits); bits--) {
		u32 out;

		if (word & (1 << 31))
			out = ioc | AR71XX_SPI_IOC_DO;
		else
			out = ioc & ~AR71XX_SPI_IOC_DO;

		/* setup MSB (to slave) on trailing edge */
		ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
		ath79_spi_delay(sp, nsecs);
		ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
		ath79_spi_delay(sp, nsecs);
		if (bits == 1)
			ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);

		word <<= 1;
	}

	return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
}

static int ath79_spi_probe(struct platform_device *pdev)
{
	struct spi_master *master;
	struct ath79_spi *sp;
	struct ath79_spi_platform_data *pdata;
	struct resource	*r;
	unsigned long rate;
	int ret;

	master = spi_alloc_master(&pdev->dev, sizeof(*sp));
	if (master == NULL) {
		dev_err(&pdev->dev, "failed to allocate spi master\n");
		return -ENOMEM;
	}

	sp = spi_master_get_devdata(master);
	platform_set_drvdata(pdev, sp);

	pdata = pdev->dev.platform_data;

	master->setup = ath79_spi_setup;
	master->cleanup = ath79_spi_cleanup;
	if (pdata) {
		master->bus_num = pdata->bus_num;
		master->num_chipselect = pdata->num_chipselect;
	}

	sp->bitbang.master = spi_master_get(master);
	sp->bitbang.chipselect = ath79_spi_chipselect;
	sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;
	sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
	sp->bitbang.flags = SPI_CS_HIGH;

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (r == NULL) {
		ret = -ENOENT;
		goto err_put_master;
	}

	sp->base = ioremap(r->start, resource_size(r));
	if (!sp->base) {
		ret = -ENXIO;
		goto err_put_master;
	}

	sp->clk = clk_get(&pdev->dev, "ahb");
	if (IS_ERR(sp->clk)) {
		ret = PTR_ERR(sp->clk);
		goto err_unmap;
	}

	ret = clk_enable(sp->clk);
	if (ret)
		goto err_clk_put;

	rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
	if (!rate) {
		ret = -EINVAL;
		goto err_clk_disable;
	}

	sp->rrw_delay = ATH79_SPI_RRW_DELAY_FACTOR / rate;
	dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
		sp->rrw_delay);

	ret = spi_bitbang_start(&sp->bitbang);
	if (ret)
		goto err_clk_disable;

	return 0;

err_clk_disable:
	clk_disable(sp->clk);
err_clk_put:
	clk_put(sp->clk);
err_unmap:
	iounmap(sp->base);
err_put_master:
	platform_set_drvdata(pdev, NULL);
	spi_master_put(sp->bitbang.master);

	return ret;
}

static int ath79_spi_remove(struct platform_device *pdev)
{
	struct ath79_spi *sp = platform_get_drvdata(pdev);

	spi_bitbang_stop(&sp->bitbang);
	clk_disable(sp->clk);
	clk_put(sp->clk);
	iounmap(sp->base);
	platform_set_drvdata(pdev, NULL);
	spi_master_put(sp->bitbang.master);

	return 0;
}

static struct platform_driver ath79_spi_driver = {
	.probe		= ath79_spi_probe,
	.remove		= ath79_spi_remove,
	.driver		= {
		.name	= DRV_NAME,
		.owner	= THIS_MODULE,
	},
};
module_platform_driver(ath79_spi_driver);

MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRV_NAME);