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/io.h>
22 #include <linux/of.h>
23
24 #define DRV_NAME "spi_altera"
25
26 #define ALTERA_SPI_RXDATA 0
27 #define ALTERA_SPI_TXDATA 4
28 #define ALTERA_SPI_STATUS 8
29 #define ALTERA_SPI_CONTROL 12
30 #define ALTERA_SPI_SLAVE_SEL 20
31
32 #define ALTERA_SPI_STATUS_ROE_MSK 0x8
33 #define ALTERA_SPI_STATUS_TOE_MSK 0x10
34 #define ALTERA_SPI_STATUS_TMT_MSK 0x20
35 #define ALTERA_SPI_STATUS_TRDY_MSK 0x40
36 #define ALTERA_SPI_STATUS_RRDY_MSK 0x80
37 #define ALTERA_SPI_STATUS_E_MSK 0x100
38
39 #define ALTERA_SPI_CONTROL_IROE_MSK 0x8
40 #define ALTERA_SPI_CONTROL_ITOE_MSK 0x10
41 #define ALTERA_SPI_CONTROL_ITRDY_MSK 0x40
42 #define ALTERA_SPI_CONTROL_IRRDY_MSK 0x80
43 #define ALTERA_SPI_CONTROL_IE_MSK 0x100
44 #define ALTERA_SPI_CONTROL_SSO_MSK 0x400
45
46 struct altera_spi {
47 void __iomem *base;
48 int irq;
49 int len;
50 int count;
51 int bytes_per_word;
52 unsigned long imr;
53
54 /* data buffers */
55 const unsigned char *tx;
56 unsigned char *rx;
57 };
58
altera_spi_to_hw(struct spi_device * sdev)59 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
60 {
61 return spi_master_get_devdata(sdev->master);
62 }
63
altera_spi_set_cs(struct spi_device * spi,bool is_high)64 static void altera_spi_set_cs(struct spi_device *spi, bool is_high)
65 {
66 struct altera_spi *hw = altera_spi_to_hw(spi);
67
68 if (is_high) {
69 hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
70 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
71 writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
72 } else {
73 writel(BIT(spi->chip_select), hw->base + ALTERA_SPI_SLAVE_SEL);
74 hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
75 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
76 }
77 }
78
altera_spi_tx_word(struct altera_spi * hw)79 static void altera_spi_tx_word(struct altera_spi *hw)
80 {
81 unsigned int txd = 0;
82
83 if (hw->tx) {
84 switch (hw->bytes_per_word) {
85 case 1:
86 txd = hw->tx[hw->count];
87 break;
88 case 2:
89 txd = (hw->tx[hw->count * 2]
90 | (hw->tx[hw->count * 2 + 1] << 8));
91 break;
92 }
93 }
94
95 writel(txd, hw->base + ALTERA_SPI_TXDATA);
96 }
97
altera_spi_rx_word(struct altera_spi * hw)98 static void altera_spi_rx_word(struct altera_spi *hw)
99 {
100 unsigned int rxd;
101
102 rxd = readl(hw->base + ALTERA_SPI_RXDATA);
103 if (hw->rx) {
104 switch (hw->bytes_per_word) {
105 case 1:
106 hw->rx[hw->count] = rxd;
107 break;
108 case 2:
109 hw->rx[hw->count * 2] = rxd;
110 hw->rx[hw->count * 2 + 1] = rxd >> 8;
111 break;
112 }
113 }
114
115 hw->count++;
116 }
117
altera_spi_txrx(struct spi_master * master,struct spi_device * spi,struct spi_transfer * t)118 static int altera_spi_txrx(struct spi_master *master,
119 struct spi_device *spi, struct spi_transfer *t)
120 {
121 struct altera_spi *hw = spi_master_get_devdata(master);
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 altera_spi_tx_word(hw);
136 } else {
137 while (hw->count < hw->len) {
138 altera_spi_tx_word(hw);
139
140 while (!(readl(hw->base + ALTERA_SPI_STATUS) &
141 ALTERA_SPI_STATUS_RRDY_MSK))
142 cpu_relax();
143
144 altera_spi_rx_word(hw);
145 }
146 spi_finalize_current_transfer(master);
147 }
148
149 return t->len;
150 }
151
altera_spi_irq(int irq,void * dev)152 static irqreturn_t altera_spi_irq(int irq, void *dev)
153 {
154 struct spi_master *master = dev;
155 struct altera_spi *hw = spi_master_get_devdata(master);
156
157 altera_spi_rx_word(hw);
158
159 if (hw->count < hw->len) {
160 altera_spi_tx_word(hw);
161 } else {
162 /* disable receive interrupt */
163 hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
164 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
165
166 spi_finalize_current_transfer(master);
167 }
168
169 return IRQ_HANDLED;
170 }
171
altera_spi_probe(struct platform_device * pdev)172 static int altera_spi_probe(struct platform_device *pdev)
173 {
174 struct altera_spi *hw;
175 struct spi_master *master;
176 struct resource *res;
177 int err = -ENODEV;
178
179 master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
180 if (!master)
181 return err;
182
183 /* setup the master state. */
184 master->bus_num = pdev->id;
185 master->num_chipselect = 16;
186 master->mode_bits = SPI_CS_HIGH;
187 master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
188 master->dev.of_node = pdev->dev.of_node;
189 master->transfer_one = altera_spi_txrx;
190 master->set_cs = altera_spi_set_cs;
191
192 hw = spi_master_get_devdata(master);
193
194 /* find and map our resources */
195 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
196 hw->base = devm_ioremap_resource(&pdev->dev, res);
197 if (IS_ERR(hw->base)) {
198 err = PTR_ERR(hw->base);
199 goto exit;
200 }
201 /* program defaults into the registers */
202 hw->imr = 0; /* disable spi interrupts */
203 writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
204 writel(0, hw->base + ALTERA_SPI_STATUS); /* clear status reg */
205 if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
206 readl(hw->base + ALTERA_SPI_RXDATA); /* flush rxdata */
207 /* irq is optional */
208 hw->irq = platform_get_irq(pdev, 0);
209 if (hw->irq >= 0) {
210 err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
211 pdev->name, master);
212 if (err)
213 goto exit;
214 }
215
216 err = devm_spi_register_master(&pdev->dev, master);
217 if (err)
218 goto exit;
219 dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
220
221 return 0;
222 exit:
223 spi_master_put(master);
224 return err;
225 }
226
227 #ifdef CONFIG_OF
228 static const struct of_device_id altera_spi_match[] = {
229 { .compatible = "ALTR,spi-1.0", },
230 { .compatible = "altr,spi-1.0", },
231 {},
232 };
233 MODULE_DEVICE_TABLE(of, altera_spi_match);
234 #endif /* CONFIG_OF */
235
236 static struct platform_driver altera_spi_driver = {
237 .probe = altera_spi_probe,
238 .driver = {
239 .name = DRV_NAME,
240 .pm = NULL,
241 .of_match_table = of_match_ptr(altera_spi_match),
242 },
243 };
244 module_platform_driver(altera_spi_driver);
245
246 MODULE_DESCRIPTION("Altera SPI driver");
247 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
248 MODULE_LICENSE("GPL");
249 MODULE_ALIAS("platform:" DRV_NAME);
250
