1 // SPDX-License-Identifier: GPL-2.0
2 //
3 // SPI controller driver for Qualcomm Atheros AR934x/QCA95xx SoCs
4 //
5 // Copyright (C) 2020 Chuanhong Guo <gch981213@gmail.com>
6 //
7 // Based on spi-mt7621.c:
8 // Copyright (C) 2011 Sergiy <piratfm@gmail.com>
9 // Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
10 // Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
11
12 #include <linux/clk.h>
13 #include <linux/io.h>
14 #include <linux/iopoll.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/of_device.h>
18 #include <linux/spi/spi.h>
19
20 #define DRIVER_NAME "spi-ar934x"
21
22 #define AR934X_SPI_REG_FS 0x00
23 #define AR934X_SPI_ENABLE BIT(0)
24
25 #define AR934X_SPI_REG_IOC 0x08
26 #define AR934X_SPI_IOC_INITVAL 0x70000
27
28 #define AR934X_SPI_REG_CTRL 0x04
29 #define AR934X_SPI_CLK_MASK GENMASK(5, 0)
30
31 #define AR934X_SPI_DATAOUT 0x10
32
33 #define AR934X_SPI_REG_SHIFT_CTRL 0x14
34 #define AR934X_SPI_SHIFT_EN BIT(31)
35 #define AR934X_SPI_SHIFT_CS(n) BIT(28 + (n))
36 #define AR934X_SPI_SHIFT_TERM 26
37 #define AR934X_SPI_SHIFT_VAL(cs, term, count) \
38 (AR934X_SPI_SHIFT_EN | AR934X_SPI_SHIFT_CS(cs) | \
39 (term) << AR934X_SPI_SHIFT_TERM | (count))
40
41 #define AR934X_SPI_DATAIN 0x18
42
43 struct ar934x_spi {
44 struct spi_controller *ctlr;
45 void __iomem *base;
46 struct clk *clk;
47 unsigned int clk_freq;
48 };
49
ar934x_spi_clk_div(struct ar934x_spi * sp,unsigned int freq)50 static inline int ar934x_spi_clk_div(struct ar934x_spi *sp, unsigned int freq)
51 {
52 int div = DIV_ROUND_UP(sp->clk_freq, freq * 2) - 1;
53
54 if (div < 0)
55 return 0;
56 else if (div > AR934X_SPI_CLK_MASK)
57 return -EINVAL;
58 else
59 return div;
60 }
61
ar934x_spi_setup(struct spi_device * spi)62 static int ar934x_spi_setup(struct spi_device *spi)
63 {
64 struct ar934x_spi *sp = spi_controller_get_devdata(spi->master);
65
66 if ((spi->max_speed_hz == 0) ||
67 (spi->max_speed_hz > (sp->clk_freq / 2))) {
68 spi->max_speed_hz = sp->clk_freq / 2;
69 } else if (spi->max_speed_hz < (sp->clk_freq / 128)) {
70 dev_err(&spi->dev, "spi clock is too low\n");
71 return -EINVAL;
72 }
73
74 return 0;
75 }
76
ar934x_spi_transfer_one_message(struct spi_controller * master,struct spi_message * m)77 static int ar934x_spi_transfer_one_message(struct spi_controller *master,
78 struct spi_message *m)
79 {
80 struct ar934x_spi *sp = spi_controller_get_devdata(master);
81 struct spi_transfer *t = NULL;
82 struct spi_device *spi = m->spi;
83 unsigned long trx_done, trx_cur;
84 int stat = 0;
85 u8 term = 0;
86 int div, i;
87 u32 reg;
88 const u8 *tx_buf;
89 u8 *buf;
90
91 m->actual_length = 0;
92 list_for_each_entry(t, &m->transfers, transfer_list) {
93 if (t->speed_hz)
94 div = ar934x_spi_clk_div(sp, t->speed_hz);
95 else
96 div = ar934x_spi_clk_div(sp, spi->max_speed_hz);
97 if (div < 0) {
98 stat = -EIO;
99 goto msg_done;
100 }
101
102 reg = ioread32(sp->base + AR934X_SPI_REG_CTRL);
103 reg &= ~AR934X_SPI_CLK_MASK;
104 reg |= div;
105 iowrite32(reg, sp->base + AR934X_SPI_REG_CTRL);
106 iowrite32(0, sp->base + AR934X_SPI_DATAOUT);
107
108 for (trx_done = 0; trx_done < t->len; trx_done += 4) {
109 trx_cur = t->len - trx_done;
110 if (trx_cur > 4)
111 trx_cur = 4;
112 else if (list_is_last(&t->transfer_list, &m->transfers))
113 term = 1;
114
115 if (t->tx_buf) {
116 tx_buf = t->tx_buf + trx_done;
117 reg = tx_buf[0];
118 for (i = 1; i < trx_cur; i++)
119 reg = reg << 8 | tx_buf[i];
120 iowrite32(reg, sp->base + AR934X_SPI_DATAOUT);
121 }
122
123 reg = AR934X_SPI_SHIFT_VAL(spi->chip_select, term,
124 trx_cur * 8);
125 iowrite32(reg, sp->base + AR934X_SPI_REG_SHIFT_CTRL);
126 stat = readl_poll_timeout(
127 sp->base + AR934X_SPI_REG_SHIFT_CTRL, reg,
128 !(reg & AR934X_SPI_SHIFT_EN), 0, 5);
129 if (stat < 0)
130 goto msg_done;
131
132 if (t->rx_buf) {
133 reg = ioread32(sp->base + AR934X_SPI_DATAIN);
134 buf = t->rx_buf + trx_done;
135 for (i = 0; i < trx_cur; i++) {
136 buf[trx_cur - i - 1] = reg & 0xff;
137 reg >>= 8;
138 }
139 }
140 }
141 m->actual_length += t->len;
142 }
143
144 msg_done:
145 m->status = stat;
146 spi_finalize_current_message(master);
147
148 return 0;
149 }
150
151 static const struct of_device_id ar934x_spi_match[] = {
152 { .compatible = "qca,ar934x-spi" },
153 {},
154 };
155 MODULE_DEVICE_TABLE(of, ar934x_spi_match);
156
ar934x_spi_probe(struct platform_device * pdev)157 static int ar934x_spi_probe(struct platform_device *pdev)
158 {
159 struct spi_controller *ctlr;
160 struct ar934x_spi *sp;
161 void __iomem *base;
162 struct clk *clk;
163 int ret;
164
165 base = devm_platform_ioremap_resource(pdev, 0);
166 if (IS_ERR(base))
167 return PTR_ERR(base);
168
169 clk = devm_clk_get(&pdev->dev, NULL);
170 if (IS_ERR(clk)) {
171 dev_err(&pdev->dev, "failed to get clock\n");
172 return PTR_ERR(clk);
173 }
174
175 ret = clk_prepare_enable(clk);
176 if (ret)
177 return ret;
178
179 ctlr = devm_spi_alloc_master(&pdev->dev, sizeof(*sp));
180 if (!ctlr) {
181 dev_info(&pdev->dev, "failed to allocate spi controller\n");
182 ret = -ENOMEM;
183 goto err_clk_disable;
184 }
185
186 /* disable flash mapping and expose spi controller registers */
187 iowrite32(AR934X_SPI_ENABLE, base + AR934X_SPI_REG_FS);
188 /* restore pins to default state: CSn=1 DO=CLK=0 */
189 iowrite32(AR934X_SPI_IOC_INITVAL, base + AR934X_SPI_REG_IOC);
190
191 ctlr->mode_bits = SPI_LSB_FIRST;
192 ctlr->setup = ar934x_spi_setup;
193 ctlr->transfer_one_message = ar934x_spi_transfer_one_message;
194 ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
195 ctlr->dev.of_node = pdev->dev.of_node;
196 ctlr->num_chipselect = 3;
197
198 dev_set_drvdata(&pdev->dev, ctlr);
199
200 sp = spi_controller_get_devdata(ctlr);
201 sp->base = base;
202 sp->clk = clk;
203 sp->clk_freq = clk_get_rate(clk);
204 sp->ctlr = ctlr;
205
206 ret = spi_register_controller(ctlr);
207 if (!ret)
208 return 0;
209
210 err_clk_disable:
211 clk_disable_unprepare(clk);
212 return ret;
213 }
214
ar934x_spi_remove(struct platform_device * pdev)215 static int ar934x_spi_remove(struct platform_device *pdev)
216 {
217 struct spi_controller *ctlr;
218 struct ar934x_spi *sp;
219
220 ctlr = dev_get_drvdata(&pdev->dev);
221 sp = spi_controller_get_devdata(ctlr);
222
223 spi_unregister_controller(ctlr);
224 clk_disable_unprepare(sp->clk);
225
226 return 0;
227 }
228
229 static struct platform_driver ar934x_spi_driver = {
230 .driver = {
231 .name = DRIVER_NAME,
232 .of_match_table = ar934x_spi_match,
233 },
234 .probe = ar934x_spi_probe,
235 .remove = ar934x_spi_remove,
236 };
237
238 module_platform_driver(ar934x_spi_driver);
239
240 MODULE_DESCRIPTION("SPI controller driver for Qualcomm Atheros AR934x/QCA95xx");
241 MODULE_AUTHOR("Chuanhong Guo <gch981213@gmail.com>");
242 MODULE_LICENSE("GPL v2");
243 MODULE_ALIAS("platform:" DRIVER_NAME);
244