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1 /*
2  * Altera SPI driver
3  *
4  * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
5  *
6  * Based on spi_s3c24xx.c, which is:
7  * Copyright (c) 2006 Ben Dooks
8  * Copyright (c) 2006 Simtec Electronics
9  *	Ben Dooks <ben@simtec.co.uk>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License version 2 as
13  * published by the Free Software Foundation.
14  */
15 
16 #include <linux/interrupt.h>
17 #include <linux/errno.h>
18 #include <linux/module.h>
19 #include <linux/platform_device.h>
20 #include <linux/spi/spi.h>
21 #include <linux/spi/spi_bitbang.h>
22 #include <linux/io.h>
23 #include <linux/of.h>
24 
25 #define DRV_NAME "spi_altera"
26 
27 #define ALTERA_SPI_RXDATA	0
28 #define ALTERA_SPI_TXDATA	4
29 #define ALTERA_SPI_STATUS	8
30 #define ALTERA_SPI_CONTROL	12
31 #define ALTERA_SPI_SLAVE_SEL	20
32 
33 #define ALTERA_SPI_STATUS_ROE_MSK	0x8
34 #define ALTERA_SPI_STATUS_TOE_MSK	0x10
35 #define ALTERA_SPI_STATUS_TMT_MSK	0x20
36 #define ALTERA_SPI_STATUS_TRDY_MSK	0x40
37 #define ALTERA_SPI_STATUS_RRDY_MSK	0x80
38 #define ALTERA_SPI_STATUS_E_MSK		0x100
39 
40 #define ALTERA_SPI_CONTROL_IROE_MSK	0x8
41 #define ALTERA_SPI_CONTROL_ITOE_MSK	0x10
42 #define ALTERA_SPI_CONTROL_ITRDY_MSK	0x40
43 #define ALTERA_SPI_CONTROL_IRRDY_MSK	0x80
44 #define ALTERA_SPI_CONTROL_IE_MSK	0x100
45 #define ALTERA_SPI_CONTROL_SSO_MSK	0x400
46 
47 struct altera_spi {
48 	/* bitbang has to be first */
49 	struct spi_bitbang bitbang;
50 	struct completion done;
51 
52 	void __iomem *base;
53 	int irq;
54 	int len;
55 	int count;
56 	int bytes_per_word;
57 	unsigned long imr;
58 
59 	/* data buffers */
60 	const unsigned char *tx;
61 	unsigned char *rx;
62 };
63 
altera_spi_to_hw(struct spi_device * sdev)64 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
65 {
66 	return spi_master_get_devdata(sdev->master);
67 }
68 
altera_spi_chipsel(struct spi_device * spi,int value)69 static void altera_spi_chipsel(struct spi_device *spi, int value)
70 {
71 	struct altera_spi *hw = altera_spi_to_hw(spi);
72 
73 	if (spi->mode & SPI_CS_HIGH) {
74 		switch (value) {
75 		case BITBANG_CS_INACTIVE:
76 			writel(1 << spi->chip_select,
77 			       hw->base + ALTERA_SPI_SLAVE_SEL);
78 			hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
79 			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
80 			break;
81 
82 		case BITBANG_CS_ACTIVE:
83 			hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
84 			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
85 			writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
86 			break;
87 		}
88 	} else {
89 		switch (value) {
90 		case BITBANG_CS_INACTIVE:
91 			hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
92 			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
93 			break;
94 
95 		case BITBANG_CS_ACTIVE:
96 			writel(1 << spi->chip_select,
97 			       hw->base + ALTERA_SPI_SLAVE_SEL);
98 			hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
99 			writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
100 			break;
101 		}
102 	}
103 }
104 
hw_txbyte(struct altera_spi * hw,int count)105 static inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
106 {
107 	if (hw->tx) {
108 		switch (hw->bytes_per_word) {
109 		case 1:
110 			return hw->tx[count];
111 		case 2:
112 			return (hw->tx[count * 2]
113 				| (hw->tx[count * 2 + 1] << 8));
114 		}
115 	}
116 	return 0;
117 }
118 
altera_spi_txrx(struct spi_device * spi,struct spi_transfer * t)119 static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
120 {
121 	struct altera_spi *hw = altera_spi_to_hw(spi);
122 
123 	hw->tx = t->tx_buf;
124 	hw->rx = t->rx_buf;
125 	hw->count = 0;
126 	hw->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
127 	hw->len = t->len / hw->bytes_per_word;
128 
129 	if (hw->irq >= 0) {
130 		/* enable receive interrupt */
131 		hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
132 		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
133 
134 		/* send the first byte */
135 		writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
136 
137 		wait_for_completion(&hw->done);
138 		/* disable receive interrupt */
139 		hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
140 		writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
141 	} else {
142 		while (hw->count < hw->len) {
143 			unsigned int rxd;
144 
145 			writel(hw_txbyte(hw, hw->count),
146 			       hw->base + ALTERA_SPI_TXDATA);
147 
148 			while (!(readl(hw->base + ALTERA_SPI_STATUS) &
149 				 ALTERA_SPI_STATUS_RRDY_MSK))
150 				cpu_relax();
151 
152 			rxd = readl(hw->base + ALTERA_SPI_RXDATA);
153 			if (hw->rx) {
154 				switch (hw->bytes_per_word) {
155 				case 1:
156 					hw->rx[hw->count] = rxd;
157 					break;
158 				case 2:
159 					hw->rx[hw->count * 2] = rxd;
160 					hw->rx[hw->count * 2 + 1] = rxd >> 8;
161 					break;
162 				}
163 			}
164 
165 			hw->count++;
166 		}
167 	}
168 
169 	return hw->count * hw->bytes_per_word;
170 }
171 
altera_spi_irq(int irq,void * dev)172 static irqreturn_t altera_spi_irq(int irq, void *dev)
173 {
174 	struct altera_spi *hw = dev;
175 	unsigned int rxd;
176 
177 	rxd = readl(hw->base + ALTERA_SPI_RXDATA);
178 	if (hw->rx) {
179 		switch (hw->bytes_per_word) {
180 		case 1:
181 			hw->rx[hw->count] = rxd;
182 			break;
183 		case 2:
184 			hw->rx[hw->count * 2] = rxd;
185 			hw->rx[hw->count * 2 + 1] = rxd >> 8;
186 			break;
187 		}
188 	}
189 
190 	hw->count++;
191 
192 	if (hw->count < hw->len)
193 		writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
194 	else
195 		complete(&hw->done);
196 
197 	return IRQ_HANDLED;
198 }
199 
altera_spi_probe(struct platform_device * pdev)200 static int altera_spi_probe(struct platform_device *pdev)
201 {
202 	struct altera_spi *hw;
203 	struct spi_master *master;
204 	struct resource *res;
205 	int err = -ENODEV;
206 
207 	master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
208 	if (!master)
209 		return err;
210 
211 	/* setup the master state. */
212 	master->bus_num = pdev->id;
213 	master->num_chipselect = 16;
214 	master->mode_bits = SPI_CS_HIGH;
215 	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
216 	master->dev.of_node = pdev->dev.of_node;
217 
218 	hw = spi_master_get_devdata(master);
219 	platform_set_drvdata(pdev, hw);
220 
221 	/* setup the state for the bitbang driver */
222 	hw->bitbang.master = master;
223 	hw->bitbang.chipselect = altera_spi_chipsel;
224 	hw->bitbang.txrx_bufs = altera_spi_txrx;
225 
226 	/* find and map our resources */
227 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
228 	hw->base = devm_ioremap_resource(&pdev->dev, res);
229 	if (IS_ERR(hw->base)) {
230 		err = PTR_ERR(hw->base);
231 		goto exit;
232 	}
233 	/* program defaults into the registers */
234 	hw->imr = 0;		/* disable spi interrupts */
235 	writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
236 	writel(0, hw->base + ALTERA_SPI_STATUS);	/* clear status reg */
237 	if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
238 		readl(hw->base + ALTERA_SPI_RXDATA);	/* flush rxdata */
239 	/* irq is optional */
240 	hw->irq = platform_get_irq(pdev, 0);
241 	if (hw->irq >= 0) {
242 		init_completion(&hw->done);
243 		err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
244 				       pdev->name, hw);
245 		if (err)
246 			goto exit;
247 	}
248 
249 	/* register our spi controller */
250 	err = spi_bitbang_start(&hw->bitbang);
251 	if (err)
252 		goto exit;
253 	dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
254 
255 	return 0;
256 exit:
257 	spi_master_put(master);
258 	return err;
259 }
260 
altera_spi_remove(struct platform_device * dev)261 static int altera_spi_remove(struct platform_device *dev)
262 {
263 	struct altera_spi *hw = platform_get_drvdata(dev);
264 	struct spi_master *master = hw->bitbang.master;
265 
266 	spi_bitbang_stop(&hw->bitbang);
267 	spi_master_put(master);
268 	return 0;
269 }
270 
271 #ifdef CONFIG_OF
272 static const struct of_device_id altera_spi_match[] = {
273 	{ .compatible = "ALTR,spi-1.0", },
274 	{ .compatible = "altr,spi-1.0", },
275 	{},
276 };
277 MODULE_DEVICE_TABLE(of, altera_spi_match);
278 #endif /* CONFIG_OF */
279 
280 static struct platform_driver altera_spi_driver = {
281 	.probe = altera_spi_probe,
282 	.remove = altera_spi_remove,
283 	.driver = {
284 		.name = DRV_NAME,
285 		.pm = NULL,
286 		.of_match_table = of_match_ptr(altera_spi_match),
287 	},
288 };
289 module_platform_driver(altera_spi_driver);
290 
291 MODULE_DESCRIPTION("Altera SPI driver");
292 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
293 MODULE_LICENSE("GPL");
294 MODULE_ALIAS("platform:" DRV_NAME);
295