xref: /linux/drivers/spi/spi-altera-core.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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_TARGET_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_controller_get_devdata(sdev->controller);
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_TARGET_SEL, 0);
81 	} else {
82 		altr_spi_writel(hw, ALTERA_SPI_TARGET_SEL,
83 				BIT(spi_get_chipselect(spi, 0)));
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_controller * host,struct spi_device * spi,struct spi_transfer * t)142 static int altera_spi_txrx(struct spi_controller *host,
143 	struct spi_device *spi, struct spi_transfer *t)
144 {
145 	struct altera_spi *hw = spi_controller_get_devdata(host);
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(host);
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_controller *host = dev;
186 	struct altera_spi *hw = spi_controller_get_devdata(host);
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(host);
198 	}
199 
200 	return IRQ_HANDLED;
201 }
202 EXPORT_SYMBOL_GPL(altera_spi_irq);
203 
altera_spi_init_host(struct spi_controller * host)204 void altera_spi_init_host(struct spi_controller *host)
205 {
206 	struct altera_spi *hw = spi_controller_get_devdata(host);
207 	u32 val;
208 
209 	host->transfer_one = altera_spi_txrx;
210 	host->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_host);
221 
222 MODULE_DESCRIPTION("Altera SPI Controller driver core");
223 MODULE_LICENSE("GPL");
224