1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * drivers/i2c/busses/i2c-mt7621.c
4 *
5 * Copyright (C) 2013 Steven Liu <steven_liu@mediatek.com>
6 * Copyright (C) 2016 Michael Lee <igvtee@gmail.com>
7 * Copyright (C) 2018 Jan Breuer <jan.breuer@jaybee.cz>
8 *
9 * Improve driver for i2cdetect from i2c-tools to detect i2c devices on the bus.
10 * (C) 2014 Sittisak <sittisaks@hotmail.com>
11 */
12
13 #include <linux/clk.h>
14 #include <linux/delay.h>
15 #include <linux/i2c.h>
16 #include <linux/io.h>
17 #include <linux/iopoll.h>
18 #include <linux/module.h>
19 #include <linux/of.h>
20 #include <linux/platform_device.h>
21 #include <linux/reset.h>
22
23 #define REG_SM0CFG2_REG 0x28
24 #define REG_SM0CTL0_REG 0x40
25 #define REG_SM0CTL1_REG 0x44
26 #define REG_SM0D0_REG 0x50
27 #define REG_SM0D1_REG 0x54
28 #define REG_PINTEN_REG 0x5c
29 #define REG_PINTST_REG 0x60
30 #define REG_PINTCL_REG 0x64
31
32 /* REG_SM0CFG2_REG */
33 #define SM0CFG2_IS_AUTOMODE BIT(0)
34
35 /* REG_SM0CTL0_REG */
36 #define SM0CTL0_ODRAIN BIT(31)
37 #define SM0CTL0_CLK_DIV_MASK (0x7ff << 16)
38 #define SM0CTL0_CLK_DIV_MAX 0x7ff
39 #define SM0CTL0_CS_STATUS BIT(4)
40 #define SM0CTL0_SCL_STATE BIT(3)
41 #define SM0CTL0_SDA_STATE BIT(2)
42 #define SM0CTL0_EN BIT(1)
43 #define SM0CTL0_SCL_STRETCH BIT(0)
44
45 /* REG_SM0CTL1_REG */
46 #define SM0CTL1_ACK_MASK (0xff << 16)
47 #define SM0CTL1_PGLEN_MASK (0x7 << 8)
48 #define SM0CTL1_PGLEN(x) ((((x) - 1) << 8) & SM0CTL1_PGLEN_MASK)
49 #define SM0CTL1_READ (5 << 4)
50 #define SM0CTL1_READ_LAST (4 << 4)
51 #define SM0CTL1_STOP (3 << 4)
52 #define SM0CTL1_WRITE (2 << 4)
53 #define SM0CTL1_START (1 << 4)
54 #define SM0CTL1_MODE_MASK (0x7 << 4)
55 #define SM0CTL1_TRI BIT(0)
56
57 /* timeout waiting for I2C devices to respond */
58 #define TIMEOUT_MS 1000
59
60 struct mtk_i2c {
61 void __iomem *base;
62 struct device *dev;
63 struct i2c_adapter adap;
64 u32 bus_freq;
65 u32 clk_div;
66 u32 flags;
67 struct clk *clk;
68 };
69
mtk_i2c_wait_idle(struct mtk_i2c * i2c)70 static int mtk_i2c_wait_idle(struct mtk_i2c *i2c)
71 {
72 int ret;
73 u32 val;
74
75 ret = readl_relaxed_poll_timeout(i2c->base + REG_SM0CTL1_REG,
76 val, !(val & SM0CTL1_TRI),
77 10, TIMEOUT_MS * 1000);
78 if (ret)
79 dev_dbg(i2c->dev, "idle err(%d)\n", ret);
80
81 return ret;
82 }
83
mtk_i2c_reset(struct mtk_i2c * i2c)84 static void mtk_i2c_reset(struct mtk_i2c *i2c)
85 {
86 int ret;
87
88 ret = device_reset(i2c->adap.dev.parent);
89 if (ret)
90 dev_err(i2c->dev, "I2C reset failed!\n");
91
92 /*
93 * Don't set SM0CTL0_ODRAIN as its bit meaning is inverted. To
94 * configure open-drain mode, this bit needs to be cleared.
95 */
96 iowrite32(((i2c->clk_div << 16) & SM0CTL0_CLK_DIV_MASK) | SM0CTL0_EN |
97 SM0CTL0_SCL_STRETCH, i2c->base + REG_SM0CTL0_REG);
98 iowrite32(0, i2c->base + REG_SM0CFG2_REG);
99 }
100
mtk_i2c_dump_reg(struct mtk_i2c * i2c)101 static void mtk_i2c_dump_reg(struct mtk_i2c *i2c)
102 {
103 dev_dbg(i2c->dev,
104 "SM0CFG2 %08x, SM0CTL0 %08x, SM0CTL1 %08x, SM0D0 %08x, SM0D1 %08x\n",
105 ioread32(i2c->base + REG_SM0CFG2_REG),
106 ioread32(i2c->base + REG_SM0CTL0_REG),
107 ioread32(i2c->base + REG_SM0CTL1_REG),
108 ioread32(i2c->base + REG_SM0D0_REG),
109 ioread32(i2c->base + REG_SM0D1_REG));
110 }
111
mtk_i2c_check_ack(struct mtk_i2c * i2c,u32 expected)112 static int mtk_i2c_check_ack(struct mtk_i2c *i2c, u32 expected)
113 {
114 u32 ack = readl_relaxed(i2c->base + REG_SM0CTL1_REG);
115 u32 ack_expected = (expected << 16) & SM0CTL1_ACK_MASK;
116
117 return ((ack & ack_expected) == ack_expected) ? 0 : -ENXIO;
118 }
119
mtk_i2c_start(struct mtk_i2c * i2c)120 static int mtk_i2c_start(struct mtk_i2c *i2c)
121 {
122 iowrite32(SM0CTL1_START | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
123 return mtk_i2c_wait_idle(i2c);
124 }
125
mtk_i2c_stop(struct mtk_i2c * i2c)126 static int mtk_i2c_stop(struct mtk_i2c *i2c)
127 {
128 iowrite32(SM0CTL1_STOP | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
129 return mtk_i2c_wait_idle(i2c);
130 }
131
mtk_i2c_cmd(struct mtk_i2c * i2c,u32 cmd,int page_len)132 static int mtk_i2c_cmd(struct mtk_i2c *i2c, u32 cmd, int page_len)
133 {
134 iowrite32(cmd | SM0CTL1_TRI | SM0CTL1_PGLEN(page_len),
135 i2c->base + REG_SM0CTL1_REG);
136 return mtk_i2c_wait_idle(i2c);
137 }
138
mtk_i2c_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)139 static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
140 int num)
141 {
142 struct mtk_i2c *i2c;
143 struct i2c_msg *pmsg;
144 u16 addr;
145 int i, j, ret, len, page_len;
146 u32 cmd;
147 u32 data[2];
148
149 i2c = i2c_get_adapdata(adap);
150
151 for (i = 0; i < num; i++) {
152 pmsg = &msgs[i];
153
154 /* wait hardware idle */
155 ret = mtk_i2c_wait_idle(i2c);
156 if (ret)
157 goto err_timeout;
158
159 /* start sequence */
160 ret = mtk_i2c_start(i2c);
161 if (ret)
162 goto err_timeout;
163
164 /* write address */
165 if (pmsg->flags & I2C_M_TEN) {
166 /* 10 bits address */
167 addr = 0xf0 | ((pmsg->addr >> 7) & 0x06);
168 addr |= (pmsg->addr & 0xff) << 8;
169 if (pmsg->flags & I2C_M_RD)
170 addr |= 1;
171 iowrite32(addr, i2c->base + REG_SM0D0_REG);
172 ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, 2);
173 if (ret)
174 goto err_timeout;
175 } else {
176 /* 7 bits address */
177 addr = i2c_8bit_addr_from_msg(pmsg);
178 iowrite32(addr, i2c->base + REG_SM0D0_REG);
179 ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, 1);
180 if (ret)
181 goto err_timeout;
182 }
183
184 /* check address ACK */
185 if (!(pmsg->flags & I2C_M_IGNORE_NAK)) {
186 ret = mtk_i2c_check_ack(i2c, BIT(0));
187 if (ret)
188 goto err_ack;
189 }
190
191 /* transfer data */
192 for (len = pmsg->len, j = 0; len > 0; len -= 8, j += 8) {
193 page_len = (len >= 8) ? 8 : len;
194
195 if (pmsg->flags & I2C_M_RD) {
196 cmd = (len > 8) ?
197 SM0CTL1_READ : SM0CTL1_READ_LAST;
198 } else {
199 memcpy(data, &pmsg->buf[j], page_len);
200 iowrite32(data[0], i2c->base + REG_SM0D0_REG);
201 iowrite32(data[1], i2c->base + REG_SM0D1_REG);
202 cmd = SM0CTL1_WRITE;
203 }
204
205 ret = mtk_i2c_cmd(i2c, cmd, page_len);
206 if (ret)
207 goto err_timeout;
208
209 if (pmsg->flags & I2C_M_RD) {
210 data[0] = ioread32(i2c->base + REG_SM0D0_REG);
211 data[1] = ioread32(i2c->base + REG_SM0D1_REG);
212 memcpy(&pmsg->buf[j], data, page_len);
213 } else {
214 if (!(pmsg->flags & I2C_M_IGNORE_NAK)) {
215 ret = mtk_i2c_check_ack(i2c,
216 (1 << page_len)
217 - 1);
218 if (ret)
219 goto err_ack;
220 }
221 }
222 }
223 }
224
225 ret = mtk_i2c_stop(i2c);
226 if (ret)
227 goto err_timeout;
228
229 /* the return value is number of executed messages */
230 return i;
231
232 err_ack:
233 ret = mtk_i2c_stop(i2c);
234 if (ret)
235 goto err_timeout;
236 return -ENXIO;
237
238 err_timeout:
239 mtk_i2c_dump_reg(i2c);
240 mtk_i2c_reset(i2c);
241 return ret;
242 }
243
mtk_i2c_func(struct i2c_adapter * a)244 static u32 mtk_i2c_func(struct i2c_adapter *a)
245 {
246 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
247 }
248
249 static const struct i2c_algorithm mtk_i2c_algo = {
250 .xfer = mtk_i2c_xfer,
251 .functionality = mtk_i2c_func,
252 };
253
254 static const struct of_device_id i2c_mtk_dt_ids[] = {
255 { .compatible = "mediatek,mt7621-i2c" },
256 { /* sentinel */ }
257 };
258
259 MODULE_DEVICE_TABLE(of, i2c_mtk_dt_ids);
260
mtk_i2c_init(struct mtk_i2c * i2c)261 static void mtk_i2c_init(struct mtk_i2c *i2c)
262 {
263 i2c->clk_div = clk_get_rate(i2c->clk) / i2c->bus_freq - 1;
264 if (i2c->clk_div < 99)
265 i2c->clk_div = 99;
266 if (i2c->clk_div > SM0CTL0_CLK_DIV_MAX)
267 i2c->clk_div = SM0CTL0_CLK_DIV_MAX;
268
269 mtk_i2c_reset(i2c);
270 }
271
mtk_i2c_probe(struct platform_device * pdev)272 static int mtk_i2c_probe(struct platform_device *pdev)
273 {
274 struct mtk_i2c *i2c;
275 struct i2c_adapter *adap;
276 int ret;
277
278 i2c = devm_kzalloc(&pdev->dev, sizeof(struct mtk_i2c), GFP_KERNEL);
279 if (!i2c)
280 return -ENOMEM;
281
282 i2c->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
283 if (IS_ERR(i2c->base))
284 return PTR_ERR(i2c->base);
285
286 i2c->clk = devm_clk_get_enabled(&pdev->dev, NULL);
287 if (IS_ERR(i2c->clk)) {
288 dev_err(&pdev->dev, "Failed to enable clock\n");
289 return PTR_ERR(i2c->clk);
290 }
291
292 i2c->dev = &pdev->dev;
293
294 if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
295 &i2c->bus_freq))
296 i2c->bus_freq = I2C_MAX_STANDARD_MODE_FREQ;
297
298 if (i2c->bus_freq == 0) {
299 dev_warn(i2c->dev, "clock-frequency 0 not supported\n");
300 return -EINVAL;
301 }
302
303 adap = &i2c->adap;
304 adap->owner = THIS_MODULE;
305 adap->algo = &mtk_i2c_algo;
306 adap->retries = 3;
307 adap->dev.parent = &pdev->dev;
308 i2c_set_adapdata(adap, i2c);
309 adap->dev.of_node = pdev->dev.of_node;
310 strscpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));
311
312 platform_set_drvdata(pdev, i2c);
313
314 mtk_i2c_init(i2c);
315
316 ret = i2c_add_adapter(adap);
317 if (ret < 0)
318 return ret;
319
320 dev_info(&pdev->dev, "clock %u kHz\n", i2c->bus_freq / 1000);
321
322 return 0;
323 }
324
mtk_i2c_remove(struct platform_device * pdev)325 static void mtk_i2c_remove(struct platform_device *pdev)
326 {
327 struct mtk_i2c *i2c = platform_get_drvdata(pdev);
328
329 i2c_del_adapter(&i2c->adap);
330 }
331
332 static struct platform_driver mtk_i2c_driver = {
333 .probe = mtk_i2c_probe,
334 .remove_new = mtk_i2c_remove,
335 .driver = {
336 .name = "i2c-mt7621",
337 .of_match_table = i2c_mtk_dt_ids,
338 },
339 };
340
341 module_platform_driver(mtk_i2c_driver);
342
343 MODULE_AUTHOR("Steven Liu");
344 MODULE_DESCRIPTION("MT7621 I2C host driver");
345 MODULE_LICENSE("GPL v2");
346 MODULE_ALIAS("platform:MT7621-I2C");
347