1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Altera SPI driver
4 *
5 * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
6 *
7 * Based on spi_s3c24xx.c, which is:
8 * Copyright (c) 2006 Ben Dooks
9 * Copyright (c) 2006 Simtec Electronics
10 * Ben Dooks <ben@simtec.co.uk>
11 */
12
13 #include <linux/errno.h>
14 #include <linux/module.h>
15 #include <linux/platform_device.h>
16 #include <linux/spi/altera.h>
17 #include <linux/spi/spi.h>
18 #include <linux/io.h>
19 #include <linux/of.h>
20
21 #define DRV_NAME "spi_altera"
22
23 #define ALTERA_SPI_RXDATA 0
24 #define ALTERA_SPI_TXDATA 4
25 #define ALTERA_SPI_STATUS 8
26 #define ALTERA_SPI_CONTROL 12
27 #define ALTERA_SPI_SLAVE_SEL 20
28
29 #define ALTERA_SPI_STATUS_ROE_MSK 0x8
30 #define ALTERA_SPI_STATUS_TOE_MSK 0x10
31 #define ALTERA_SPI_STATUS_TMT_MSK 0x20
32 #define ALTERA_SPI_STATUS_TRDY_MSK 0x40
33 #define ALTERA_SPI_STATUS_RRDY_MSK 0x80
34 #define ALTERA_SPI_STATUS_E_MSK 0x100
35
36 #define ALTERA_SPI_CONTROL_IROE_MSK 0x8
37 #define ALTERA_SPI_CONTROL_ITOE_MSK 0x10
38 #define ALTERA_SPI_CONTROL_ITRDY_MSK 0x40
39 #define ALTERA_SPI_CONTROL_IRRDY_MSK 0x80
40 #define ALTERA_SPI_CONTROL_IE_MSK 0x100
41 #define ALTERA_SPI_CONTROL_SSO_MSK 0x400
42
altr_spi_writel(struct altera_spi * hw,unsigned int reg,unsigned int val)43 static int altr_spi_writel(struct altera_spi *hw, unsigned int reg,
44 unsigned int val)
45 {
46 int ret;
47
48 ret = regmap_write(hw->regmap, hw->regoff + reg, val);
49 if (ret)
50 dev_err(hw->dev, "fail to write reg 0x%x val 0x%x: %d\n",
51 reg, val, ret);
52
53 return ret;
54 }
55
altr_spi_readl(struct altera_spi * hw,unsigned int reg,unsigned int * val)56 static int altr_spi_readl(struct altera_spi *hw, unsigned int reg,
57 unsigned int *val)
58 {
59 int ret;
60
61 ret = regmap_read(hw->regmap, hw->regoff + reg, val);
62 if (ret)
63 dev_err(hw->dev, "fail to read reg 0x%x: %d\n", reg, ret);
64
65 return ret;
66 }
67
altera_spi_to_hw(struct spi_device * sdev)68 static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
69 {
70 return spi_master_get_devdata(sdev->master);
71 }
72
altera_spi_set_cs(struct spi_device * spi,bool is_high)73 static void altera_spi_set_cs(struct spi_device *spi, bool is_high)
74 {
75 struct altera_spi *hw = altera_spi_to_hw(spi);
76
77 if (is_high) {
78 hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
79 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
80 altr_spi_writel(hw, ALTERA_SPI_SLAVE_SEL, 0);
81 } else {
82 altr_spi_writel(hw, ALTERA_SPI_SLAVE_SEL,
83 BIT(spi->chip_select));
84 hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
85 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
86 }
87 }
88
altera_spi_tx_word(struct altera_spi * hw)89 static void altera_spi_tx_word(struct altera_spi *hw)
90 {
91 unsigned int txd = 0;
92
93 if (hw->tx) {
94 switch (hw->bytes_per_word) {
95 case 1:
96 txd = hw->tx[hw->count];
97 break;
98 case 2:
99 txd = (hw->tx[hw->count * 2]
100 | (hw->tx[hw->count * 2 + 1] << 8));
101 break;
102 case 4:
103 txd = (hw->tx[hw->count * 4]
104 | (hw->tx[hw->count * 4 + 1] << 8)
105 | (hw->tx[hw->count * 4 + 2] << 16)
106 | (hw->tx[hw->count * 4 + 3] << 24));
107 break;
108
109 }
110 }
111
112 altr_spi_writel(hw, ALTERA_SPI_TXDATA, txd);
113 }
114
altera_spi_rx_word(struct altera_spi * hw)115 static void altera_spi_rx_word(struct altera_spi *hw)
116 {
117 unsigned int rxd;
118
119 altr_spi_readl(hw, ALTERA_SPI_RXDATA, &rxd);
120 if (hw->rx) {
121 switch (hw->bytes_per_word) {
122 case 1:
123 hw->rx[hw->count] = rxd;
124 break;
125 case 2:
126 hw->rx[hw->count * 2] = rxd;
127 hw->rx[hw->count * 2 + 1] = rxd >> 8;
128 break;
129 case 4:
130 hw->rx[hw->count * 4] = rxd;
131 hw->rx[hw->count * 4 + 1] = rxd >> 8;
132 hw->rx[hw->count * 4 + 2] = rxd >> 16;
133 hw->rx[hw->count * 4 + 3] = rxd >> 24;
134 break;
135
136 }
137 }
138
139 hw->count++;
140 }
141
altera_spi_txrx(struct spi_master * master,struct spi_device * spi,struct spi_transfer * t)142 static int altera_spi_txrx(struct spi_master *master,
143 struct spi_device *spi, struct spi_transfer *t)
144 {
145 struct altera_spi *hw = spi_master_get_devdata(master);
146 u32 val;
147
148 hw->tx = t->tx_buf;
149 hw->rx = t->rx_buf;
150 hw->count = 0;
151 hw->bytes_per_word = DIV_ROUND_UP(t->bits_per_word, 8);
152 hw->len = t->len / hw->bytes_per_word;
153
154 if (hw->irq >= 0) {
155 /* enable receive interrupt */
156 hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
157 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
158
159 /* send the first byte */
160 altera_spi_tx_word(hw);
161
162 return 1;
163 }
164
165 while (hw->count < hw->len) {
166 altera_spi_tx_word(hw);
167
168 for (;;) {
169 altr_spi_readl(hw, ALTERA_SPI_STATUS, &val);
170 if (val & ALTERA_SPI_STATUS_RRDY_MSK)
171 break;
172
173 cpu_relax();
174 }
175
176 altera_spi_rx_word(hw);
177 }
178 spi_finalize_current_transfer(master);
179
180 return 0;
181 }
182
altera_spi_irq(int irq,void * dev)183 irqreturn_t altera_spi_irq(int irq, void *dev)
184 {
185 struct spi_master *master = dev;
186 struct altera_spi *hw = spi_master_get_devdata(master);
187
188 altera_spi_rx_word(hw);
189
190 if (hw->count < hw->len) {
191 altera_spi_tx_word(hw);
192 } else {
193 /* disable receive interrupt */
194 hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
195 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
196
197 spi_finalize_current_transfer(master);
198 }
199
200 return IRQ_HANDLED;
201 }
202 EXPORT_SYMBOL_GPL(altera_spi_irq);
203
altera_spi_init_master(struct spi_master * master)204 void altera_spi_init_master(struct spi_master *master)
205 {
206 struct altera_spi *hw = spi_master_get_devdata(master);
207 u32 val;
208
209 master->transfer_one = altera_spi_txrx;
210 master->set_cs = altera_spi_set_cs;
211
212 /* program defaults into the registers */
213 hw->imr = 0; /* disable spi interrupts */
214 altr_spi_writel(hw, ALTERA_SPI_CONTROL, hw->imr);
215 altr_spi_writel(hw, ALTERA_SPI_STATUS, 0); /* clear status reg */
216 altr_spi_readl(hw, ALTERA_SPI_STATUS, &val);
217 if (val & ALTERA_SPI_STATUS_RRDY_MSK)
218 altr_spi_readl(hw, ALTERA_SPI_RXDATA, &val); /* flush rxdata */
219 }
220 EXPORT_SYMBOL_GPL(altera_spi_init_master);
221
222 MODULE_LICENSE("GPL");
223