summaryrefslogtreecommitdiffstats
path: root/drivers/spi/spi-oc-tiny.c
blob: 6ea38f5e7d64f58007e54630e0198044e5645724 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * OpenCores tiny SPI host driver
 *
 * https://opencores.org/project,tiny_spi
 *
 * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw>
 *
 * Based on spi_s3c24xx.c, which is:
 * Copyright (c) 2006 Ben Dooks
 * Copyright (c) 2006 Simtec Electronics
 *	Ben Dooks <ben@simtec.co.uk>
 */

#include <linux/interrupt.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#include <linux/spi/spi_oc_tiny.h>
#include <linux/io.h>
#include <linux/of.h>

#define DRV_NAME "spi_oc_tiny"

#define TINY_SPI_RXDATA 0
#define TINY_SPI_TXDATA 4
#define TINY_SPI_STATUS 8
#define TINY_SPI_CONTROL 12
#define TINY_SPI_BAUD 16

#define TINY_SPI_STATUS_TXE 0x1
#define TINY_SPI_STATUS_TXR 0x2

struct tiny_spi {
	/* bitbang has to be first */
	struct spi_bitbang bitbang;
	struct completion done;

	void __iomem *base;
	int irq;
	unsigned int freq;
	unsigned int baudwidth;
	unsigned int baud;
	unsigned int speed_hz;
	unsigned int mode;
	unsigned int len;
	unsigned int txc, rxc;
	const u8 *txp;
	u8 *rxp;
};

static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev)
{
	return spi_controller_get_devdata(sdev->controller);
}

static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz)
{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);

	return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1;
}

static int tiny_spi_setup_transfer(struct spi_device *spi,
				   struct spi_transfer *t)
{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);
	unsigned int baud = hw->baud;

	if (t) {
		if (t->speed_hz && t->speed_hz != hw->speed_hz)
			baud = tiny_spi_baud(spi, t->speed_hz);
	}
	writel(baud, hw->base + TINY_SPI_BAUD);
	writel(hw->mode, hw->base + TINY_SPI_CONTROL);
	return 0;
}

static int tiny_spi_setup(struct spi_device *spi)
{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);

	if (spi->max_speed_hz != hw->speed_hz) {
		hw->speed_hz = spi->max_speed_hz;
		hw->baud = tiny_spi_baud(spi, hw->speed_hz);
	}
	hw->mode = spi->mode & SPI_MODE_X_MASK;
	return 0;
}

static inline void tiny_spi_wait_txr(struct tiny_spi *hw)
{
	while (!(readb(hw->base + TINY_SPI_STATUS) &
		 TINY_SPI_STATUS_TXR))
		cpu_relax();
}

static inline void tiny_spi_wait_txe(struct tiny_spi *hw)
{
	while (!(readb(hw->base + TINY_SPI_STATUS) &
		 TINY_SPI_STATUS_TXE))
		cpu_relax();
}

static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t)
{
	struct tiny_spi *hw = tiny_spi_to_hw(spi);
	const u8 *txp = t->tx_buf;
	u8 *rxp = t->rx_buf;
	unsigned int i;

	if (hw->irq >= 0) {
		/* use interrupt driven data transfer */
		hw->len = t->len;
		hw->txp = t->tx_buf;
		hw->rxp = t->rx_buf;
		hw->txc = 0;
		hw->rxc = 0;

		/* send the first byte */
		if (t->len > 1) {
			writeb(hw->txp ? *hw->txp++ : 0,
			       hw->base + TINY_SPI_TXDATA);
			hw->txc++;
			writeb(hw->txp ? *hw->txp++ : 0,
			       hw->base + TINY_SPI_TXDATA);
			hw->txc++;
			writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS);
		} else {
			writeb(hw->txp ? *hw->txp++ : 0,
			       hw->base + TINY_SPI_TXDATA);
			hw->txc++;
			writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS);
		}

		wait_for_completion(&hw->done);
	} else {
		/* we need to tighten the transfer loop */
		writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);
		for (i = 1; i < t->len; i++) {
			writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA);

			if (rxp || (i != t->len - 1))
				tiny_spi_wait_txr(hw);
			if (rxp)
				*rxp++ = readb(hw->base + TINY_SPI_TXDATA);
		}
		tiny_spi_wait_txe(hw);
		if (rxp)
			*rxp++ = readb(hw->base + TINY_SPI_RXDATA);
	}

	return t->len;
}

static irqreturn_t tiny_spi_irq(int irq, void *dev)
{
	struct tiny_spi *hw = dev;

	writeb(0, hw->base + TINY_SPI_STATUS);
	if (hw->rxc + 1 == hw->len) {
		if (hw->rxp)
			*hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA);
		hw->rxc++;
		complete(&hw->done);
	} else {
		if (hw->rxp)
			*hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA);
		hw->rxc++;
		if (hw->txc < hw->len) {
			writeb(hw->txp ? *hw->txp++ : 0,
			       hw->base + TINY_SPI_TXDATA);
			hw->txc++;
			writeb(TINY_SPI_STATUS_TXR,
			       hw->base + TINY_SPI_STATUS);
		} else {
			writeb(TINY_SPI_STATUS_TXE,
			       hw->base + TINY_SPI_STATUS);
		}
	}
	return IRQ_HANDLED;
}

#ifdef CONFIG_OF
#include <linux/of_gpio.h>

static int tiny_spi_of_probe(struct platform_device *pdev)
{
	struct tiny_spi *hw = platform_get_drvdata(pdev);
	struct device_node *np = pdev->dev.of_node;
	u32 val;

	if (!np)
		return 0;
	hw->bitbang.ctlr->dev.of_node = pdev->dev.of_node;
	if (!of_property_read_u32(np, "clock-frequency", &val))
		hw->freq = val;
	if (!of_property_read_u32(np, "baud-width", &val))
		hw->baudwidth = val;
	return 0;
}
#else /* !CONFIG_OF */
static int tiny_spi_of_probe(struct platform_device *pdev)
{
	return 0;
}
#endif /* CONFIG_OF */

static int tiny_spi_probe(struct platform_device *pdev)
{
	struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev);
	struct tiny_spi *hw;
	struct spi_controller *host;
	int err = -ENODEV;

	host = spi_alloc_host(&pdev->dev, sizeof(struct tiny_spi));
	if (!host)
		return err;

	/* setup the host state. */
	host->bus_num = pdev->id;
	host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
	host->setup = tiny_spi_setup;
	host->use_gpio_descriptors = true;

	hw = spi_controller_get_devdata(host);
	platform_set_drvdata(pdev, hw);

	/* setup the state for the bitbang driver */
	hw->bitbang.ctlr = host;
	hw->bitbang.setup_transfer = tiny_spi_setup_transfer;
	hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs;

	/* find and map our resources */
	hw->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(hw->base)) {
		err = PTR_ERR(hw->base);
		goto exit;
	}
	/* irq is optional */
	hw->irq = platform_get_irq(pdev, 0);
	if (hw->irq >= 0) {
		init_completion(&hw->done);
		err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0,
				       pdev->name, hw);
		if (err)
			goto exit;
	}
	/* find platform data */
	if (platp) {
		hw->freq = platp->freq;
		hw->baudwidth = platp->baudwidth;
	} else {
		err = tiny_spi_of_probe(pdev);
		if (err)
			goto exit;
	}

	/* register our spi controller */
	err = spi_bitbang_start(&hw->bitbang);
	if (err)
		goto exit;
	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);

	return 0;

exit:
	spi_controller_put(host);
	return err;
}

static void tiny_spi_remove(struct platform_device *pdev)
{
	struct tiny_spi *hw = platform_get_drvdata(pdev);
	struct spi_controller *host = hw->bitbang.ctlr;

	spi_bitbang_stop(&hw->bitbang);
	spi_controller_put(host);
}

#ifdef CONFIG_OF
static const struct of_device_id tiny_spi_match[] = {
	{ .compatible = "opencores,tiny-spi-rtlsvn2", },
	{},
};
MODULE_DEVICE_TABLE(of, tiny_spi_match);
#endif /* CONFIG_OF */

static struct platform_driver tiny_spi_driver = {
	.probe = tiny_spi_probe,
	.remove_new = tiny_spi_remove,
	.driver = {
		.name = DRV_NAME,
		.pm = NULL,
		.of_match_table = of_match_ptr(tiny_spi_match),
	},
};
module_platform_driver(tiny_spi_driver);

MODULE_DESCRIPTION("OpenCores tiny SPI driver");
MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);