1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * (C) Copyright 2017 - Beniamino Galvani <b.galvani@gmail.com>
4 */
5 #include <common.h>
6 #include <log.h>
7 #include <asm/io.h>
8 #include <clk.h>
9 #include <dm.h>
10 #include <i2c.h>
11 #include <linux/bitops.h>
12 #include <linux/delay.h>
13 #include <linux/err.h>
14
15 #define I2C_TIMEOUT_MS 100
16
17 /* Control register fields */
18 #define REG_CTRL_START BIT(0)
19 #define REG_CTRL_ACK_IGNORE BIT(1)
20 #define REG_CTRL_STATUS BIT(2)
21 #define REG_CTRL_ERROR BIT(3)
22 #define REG_CTRL_CLKDIV_SHIFT 12
23 #define REG_CTRL_CLKDIV_MASK GENMASK(21, 12)
24 #define REG_CTRL_CLKDIVEXT_SHIFT 28
25 #define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, 28)
26
27 enum {
28 TOKEN_END = 0,
29 TOKEN_START,
30 TOKEN_SLAVE_ADDR_WRITE,
31 TOKEN_SLAVE_ADDR_READ,
32 TOKEN_DATA,
33 TOKEN_DATA_LAST,
34 TOKEN_STOP,
35 };
36
37 struct i2c_regs {
38 u32 ctrl;
39 u32 slave_addr;
40 u32 tok_list0;
41 u32 tok_list1;
42 u32 tok_wdata0;
43 u32 tok_wdata1;
44 u32 tok_rdata0;
45 u32 tok_rdata1;
46 };
47
48 struct meson_i2c_data {
49 unsigned char div_factor;
50 };
51
52 struct meson_i2c {
53 const struct meson_i2c_data *data;
54 struct clk clk;
55 struct i2c_regs *regs;
56 struct i2c_msg *msg; /* Current I2C message */
57 bool last; /* Whether the message is the last */
58 uint count; /* Number of bytes in the current transfer */
59 uint pos; /* Position of current transfer in message */
60 u32 tokens[2]; /* Sequence of tokens to be written */
61 uint num_tokens; /* Number of tokens to be written */
62 };
63
meson_i2c_reset_tokens(struct meson_i2c * i2c)64 static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
65 {
66 i2c->tokens[0] = 0;
67 i2c->tokens[1] = 0;
68 i2c->num_tokens = 0;
69 }
70
meson_i2c_add_token(struct meson_i2c * i2c,int token)71 static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
72 {
73 if (i2c->num_tokens < 8)
74 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
75 else
76 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
77
78 i2c->num_tokens++;
79 }
80
81 /*
82 * Retrieve data for the current transfer (which can be at most 8
83 * bytes) from the device internal buffer.
84 */
meson_i2c_get_data(struct meson_i2c * i2c,u8 * buf,int len)85 static void meson_i2c_get_data(struct meson_i2c *i2c, u8 *buf, int len)
86 {
87 u32 rdata0, rdata1;
88 int i;
89
90 rdata0 = readl(&i2c->regs->tok_rdata0);
91 rdata1 = readl(&i2c->regs->tok_rdata1);
92
93 debug("meson i2c: read data %08x %08x len %d\n", rdata0, rdata1, len);
94
95 for (i = 0; i < min(4, len); i++)
96 *buf++ = (rdata0 >> i * 8) & 0xff;
97
98 for (i = 4; i < min(8, len); i++)
99 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
100 }
101
102 /*
103 * Write data for the current transfer (which can be at most 8 bytes)
104 * to the device internal buffer.
105 */
meson_i2c_put_data(struct meson_i2c * i2c,u8 * buf,int len)106 static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
107 {
108 u32 wdata0 = 0, wdata1 = 0;
109 int i;
110
111 for (i = 0; i < min(4, len); i++)
112 wdata0 |= *buf++ << (i * 8);
113
114 for (i = 4; i < min(8, len); i++)
115 wdata1 |= *buf++ << ((i - 4) * 8);
116
117 writel(wdata0, &i2c->regs->tok_wdata0);
118 writel(wdata1, &i2c->regs->tok_wdata1);
119
120 debug("meson i2c: write data %08x %08x len %d\n", wdata0, wdata1, len);
121 }
122
123 /*
124 * Prepare the next transfer: pick the next 8 bytes in the remaining
125 * part of message and write tokens and data (if needed) to the
126 * device.
127 */
meson_i2c_prepare_xfer(struct meson_i2c * i2c)128 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
129 {
130 bool write = !(i2c->msg->flags & I2C_M_RD);
131 int i;
132
133 i2c->count = min(i2c->msg->len - i2c->pos, 8u);
134
135 for (i = 0; i + 1 < i2c->count; i++)
136 meson_i2c_add_token(i2c, TOKEN_DATA);
137
138 if (i2c->count) {
139 if (write || i2c->pos + i2c->count < i2c->msg->len)
140 meson_i2c_add_token(i2c, TOKEN_DATA);
141 else
142 meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
143 }
144
145 if (write)
146 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
147
148 if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
149 meson_i2c_add_token(i2c, TOKEN_STOP);
150
151 writel(i2c->tokens[0], &i2c->regs->tok_list0);
152 writel(i2c->tokens[1], &i2c->regs->tok_list1);
153 }
154
meson_i2c_do_start(struct meson_i2c * i2c,struct i2c_msg * msg)155 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
156 {
157 int token;
158
159 token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
160 TOKEN_SLAVE_ADDR_WRITE;
161
162 writel(msg->addr << 1, &i2c->regs->slave_addr);
163 meson_i2c_add_token(i2c, TOKEN_START);
164 meson_i2c_add_token(i2c, token);
165 }
166
meson_i2c_xfer_msg(struct meson_i2c * i2c,struct i2c_msg * msg,int last)167 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
168 int last)
169 {
170 ulong start;
171
172 debug("meson i2c: %s addr %u len %u\n",
173 (msg->flags & I2C_M_RD) ? "read" : "write",
174 msg->addr, msg->len);
175
176 i2c->msg = msg;
177 i2c->last = last;
178 i2c->pos = 0;
179 i2c->count = 0;
180
181 meson_i2c_reset_tokens(i2c);
182 meson_i2c_do_start(i2c, msg);
183
184 do {
185 meson_i2c_prepare_xfer(i2c);
186
187 /* start the transfer */
188 setbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
189 start = get_timer(0);
190 while (readl(&i2c->regs->ctrl) & REG_CTRL_STATUS) {
191 if (get_timer(start) > I2C_TIMEOUT_MS) {
192 clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
193 debug("meson i2c: timeout\n");
194 return -ETIMEDOUT;
195 }
196 udelay(1);
197 }
198 meson_i2c_reset_tokens(i2c);
199 clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
200
201 if (readl(&i2c->regs->ctrl) & REG_CTRL_ERROR) {
202 debug("meson i2c: error\n");
203 return -EREMOTEIO;
204 }
205
206 if ((msg->flags & I2C_M_RD) && i2c->count) {
207 meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
208 i2c->count);
209 }
210 i2c->pos += i2c->count;
211 } while (i2c->pos < msg->len);
212
213 return 0;
214 }
215
meson_i2c_xfer(struct udevice * bus,struct i2c_msg * msg,int nmsgs)216 static int meson_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
217 int nmsgs)
218 {
219 struct meson_i2c *i2c = dev_get_priv(bus);
220 int i, ret = 0;
221
222 for (i = 0; i < nmsgs; i++) {
223 ret = meson_i2c_xfer_msg(i2c, msg + i, i == nmsgs - 1);
224 if (ret)
225 return ret;
226 }
227
228 return 0;
229 }
230
meson_i2c_set_bus_speed(struct udevice * bus,unsigned int speed)231 static int meson_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
232 {
233 struct meson_i2c *i2c = dev_get_priv(bus);
234 ulong clk_rate;
235 unsigned int div;
236
237 clk_rate = clk_get_rate(&i2c->clk);
238 if (IS_ERR_VALUE(clk_rate))
239 return -EINVAL;
240
241 div = DIV_ROUND_UP(clk_rate, speed * i2c->data->div_factor);
242
243 /* clock divider has 12 bits */
244 if (div >= (1 << 12)) {
245 debug("meson i2c: requested bus frequency too low\n");
246 div = (1 << 12) - 1;
247 }
248
249 clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIV_MASK,
250 (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
251
252 clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIVEXT_MASK,
253 (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
254
255 debug("meson i2c: set clk %u, src %lu, div %u\n", speed, clk_rate, div);
256
257 return 0;
258 }
259
meson_i2c_probe(struct udevice * bus)260 static int meson_i2c_probe(struct udevice *bus)
261 {
262 struct meson_i2c *i2c = dev_get_priv(bus);
263 int ret;
264
265 i2c->data = (const struct meson_i2c_data *)dev_get_driver_data(bus);
266
267 ret = clk_get_by_index(bus, 0, &i2c->clk);
268 if (ret < 0)
269 return ret;
270
271 ret = clk_enable(&i2c->clk);
272 if (ret)
273 return ret;
274
275 i2c->regs = dev_read_addr_ptr(bus);
276 clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
277
278 return 0;
279 }
280
281 static const struct dm_i2c_ops meson_i2c_ops = {
282 .xfer = meson_i2c_xfer,
283 .set_bus_speed = meson_i2c_set_bus_speed,
284 };
285
286 static const struct meson_i2c_data i2c_meson6_data = {
287 .div_factor = 4,
288 };
289
290 static const struct meson_i2c_data i2c_gxbb_data = {
291 .div_factor = 4,
292 };
293
294 static const struct meson_i2c_data i2c_axg_data = {
295 .div_factor = 3,
296 };
297
298 static const struct udevice_id meson_i2c_ids[] = {
299 {.compatible = "amlogic,meson6-i2c", .data = (ulong)&i2c_meson6_data},
300 {.compatible = "amlogic,meson-gx-i2c", .data = (ulong)&i2c_gxbb_data},
301 {.compatible = "amlogic,meson-gxbb-i2c", .data = (ulong)&i2c_gxbb_data},
302 {.compatible = "amlogic,meson-axg-i2c", .data = (ulong)&i2c_axg_data},
303 {}
304 };
305
306 U_BOOT_DRIVER(i2c_meson) = {
307 .name = "i2c_meson",
308 .id = UCLASS_I2C,
309 .of_match = meson_i2c_ids,
310 .probe = meson_i2c_probe,
311 .priv_auto = sizeof(struct meson_i2c),
312 .ops = &meson_i2c_ops,
313 };
314