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Linux/drivers/spi/spi-altera.c

  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 
 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 
 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 
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 
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 
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 
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 
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                 .owner = THIS_MODULE,
286                 .pm = NULL,
287                 .of_match_table = of_match_ptr(altera_spi_match),
288         },
289 };
290 module_platform_driver(altera_spi_driver);
291 
292 MODULE_DESCRIPTION("Altera SPI driver");
293 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
294 MODULE_LICENSE("GPL");
295 MODULE_ALIAS("platform:" DRV_NAME);
296 

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