2 * I2C bus driver for Amlogic Meson SoCs
4 * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <linux/clk.h>
12 #include <linux/completion.h>
13 #include <linux/i2c.h>
14 #include <linux/interrupt.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
19 #include <linux/platform_device.h>
20 #include <linux/types.h>
22 /* Meson I2C register map */
24 #define REG_SLAVE_ADDR 0x04
25 #define REG_TOK_LIST0 0x08
26 #define REG_TOK_LIST1 0x0c
27 #define REG_TOK_WDATA0 0x10
28 #define REG_TOK_WDATA1 0x14
29 #define REG_TOK_RDATA0 0x18
30 #define REG_TOK_RDATA1 0x1c
32 /* Control register fields */
33 #define REG_CTRL_START BIT(0)
34 #define REG_CTRL_ACK_IGNORE BIT(1)
35 #define REG_CTRL_STATUS BIT(2)
36 #define REG_CTRL_ERROR BIT(3)
37 #define REG_CTRL_CLKDIV_SHIFT 12
38 #define REG_CTRL_CLKDIV_MASK GENMASK(21, 12)
39 #define REG_CTRL_CLKDIVEXT_SHIFT 28
40 #define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, 28)
42 #define I2C_TIMEOUT_MS 500
47 TOKEN_SLAVE_ADDR_WRITE,
48 TOKEN_SLAVE_ADDR_READ,
62 * struct meson_i2c - Meson I2C device private data
64 * @adap: I2C adapter instance
65 * @dev: Pointer to device structure
66 * @regs: Base address of the device memory mapped registers
67 * @clk: Pointer to clock structure
69 * @msg: Pointer to the current I2C message
70 * @state: Current state in the driver state machine
71 * @last: Flag set for the last message in the transfer
72 * @count: Number of bytes to be sent/received in current transfer
73 * @pos: Current position in the send/receive buffer
74 * @error: Flag set when an error is received
75 * @lock: To avoid race conditions between irq handler and xfer code
76 * @done: Completion used to wait for transfer termination
77 * @tokens: Sequence of tokens to be written to the device
78 * @num_tokens: Number of tokens
81 struct i2c_adapter adap;
94 struct completion done;
99 static void meson_i2c_set_mask(struct meson_i2c *i2c, int reg, u32 mask,
104 data = readl(i2c->regs + reg);
107 writel(data, i2c->regs + reg);
110 static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
117 static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
119 if (i2c->num_tokens < 8)
120 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
122 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
127 static void meson_i2c_write_tokens(struct meson_i2c *i2c)
129 writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
130 writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
133 static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
135 unsigned long clk_rate = clk_get_rate(i2c->clk);
138 div = DIV_ROUND_UP(clk_rate, freq * 4);
140 /* clock divider has 12 bits */
141 if (div >= (1 << 12)) {
142 dev_err(i2c->dev, "requested bus frequency too low\n");
146 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
147 (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
149 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
150 (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
152 dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
153 clk_rate, freq, div);
156 static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
161 rdata0 = readl(i2c->regs + REG_TOK_RDATA0);
162 rdata1 = readl(i2c->regs + REG_TOK_RDATA1);
164 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
165 rdata0, rdata1, len);
167 for (i = 0; i < min(4, len); i++)
168 *buf++ = (rdata0 >> i * 8) & 0xff;
170 for (i = 4; i < min(8, len); i++)
171 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
174 static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len)
176 u32 wdata0 = 0, wdata1 = 0;
179 for (i = 0; i < min(4, len); i++)
180 wdata0 |= *buf++ << (i * 8);
182 for (i = 4; i < min(8, len); i++)
183 wdata1 |= *buf++ << ((i - 4) * 8);
185 writel(wdata0, i2c->regs + REG_TOK_WDATA0);
186 writel(wdata1, i2c->regs + REG_TOK_WDATA1);
188 dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
189 wdata0, wdata1, len);
192 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
194 bool write = !(i2c->msg->flags & I2C_M_RD);
197 i2c->count = min(i2c->msg->len - i2c->pos, 8);
199 for (i = 0; i < i2c->count - 1; i++)
200 meson_i2c_add_token(i2c, TOKEN_DATA);
203 if (write || i2c->pos + i2c->count < i2c->msg->len)
204 meson_i2c_add_token(i2c, TOKEN_DATA);
206 meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
210 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
213 static void meson_i2c_stop(struct meson_i2c *i2c)
215 dev_dbg(i2c->dev, "%s: last %d\n", __func__, i2c->last);
218 i2c->state = STATE_STOP;
219 meson_i2c_add_token(i2c, TOKEN_STOP);
221 i2c->state = STATE_IDLE;
222 complete(&i2c->done);
226 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
228 struct meson_i2c *i2c = dev_id;
231 spin_lock(&i2c->lock);
233 meson_i2c_reset_tokens(i2c);
234 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
235 ctrl = readl(i2c->regs + REG_CTRL);
237 dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
238 i2c->state, i2c->pos, i2c->count, ctrl);
240 if (i2c->state == STATE_IDLE) {
241 spin_unlock(&i2c->lock);
245 if (ctrl & REG_CTRL_ERROR) {
247 * The bit is set when the IGNORE_NAK bit is cleared
248 * and the device didn't respond. In this case, the
249 * I2C controller automatically generates a STOP
252 dev_dbg(i2c->dev, "error bit set\n");
254 i2c->state = STATE_IDLE;
255 complete(&i2c->done);
259 switch (i2c->state) {
261 if (i2c->count > 0) {
262 meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
264 i2c->pos += i2c->count;
267 if (i2c->pos >= i2c->msg->len) {
272 meson_i2c_prepare_xfer(i2c);
275 i2c->pos += i2c->count;
277 if (i2c->pos >= i2c->msg->len) {
282 meson_i2c_prepare_xfer(i2c);
285 i2c->state = STATE_IDLE;
286 complete(&i2c->done);
291 if (i2c->state != STATE_IDLE) {
292 /* Restart the processing */
293 meson_i2c_write_tokens(i2c);
294 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START,
298 spin_unlock(&i2c->lock);
303 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
307 token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
308 TOKEN_SLAVE_ADDR_WRITE;
310 writel(msg->addr << 1, i2c->regs + REG_SLAVE_ADDR);
311 meson_i2c_add_token(i2c, TOKEN_START);
312 meson_i2c_add_token(i2c, token);
315 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
318 unsigned long time_left, flags;
327 meson_i2c_reset_tokens(i2c);
329 flags = (msg->flags & I2C_M_IGNORE_NAK) ? REG_CTRL_ACK_IGNORE : 0;
330 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_ACK_IGNORE, flags);
332 if (!(msg->flags & I2C_M_NOSTART))
333 meson_i2c_do_start(i2c, msg);
335 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
336 meson_i2c_prepare_xfer(i2c);
337 meson_i2c_write_tokens(i2c);
338 reinit_completion(&i2c->done);
340 /* Start the transfer */
341 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
343 time_left = msecs_to_jiffies(I2C_TIMEOUT_MS);
344 time_left = wait_for_completion_timeout(&i2c->done, time_left);
347 * Protect access to i2c struct and registers from interrupt
348 * handlers triggered by a transfer terminated after the
351 spin_lock_irqsave(&i2c->lock, flags);
353 /* Abort any active operation */
354 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
357 i2c->state = STATE_IDLE;
364 spin_unlock_irqrestore(&i2c->lock, flags);
369 static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
372 struct meson_i2c *i2c = adap->algo_data;
375 clk_enable(i2c->clk);
377 for (i = 0; i < num; i++) {
378 ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1);
383 clk_disable(i2c->clk);
388 static u32 meson_i2c_func(struct i2c_adapter *adap)
390 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
393 static const struct i2c_algorithm meson_i2c_algorithm = {
394 .master_xfer = meson_i2c_xfer,
395 .functionality = meson_i2c_func,
398 static int meson_i2c_probe(struct platform_device *pdev)
400 struct device_node *np = pdev->dev.of_node;
401 struct meson_i2c *i2c;
402 struct resource *mem;
403 struct i2c_timings timings;
406 i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
410 i2c_parse_fw_timings(&pdev->dev, &timings, true);
412 i2c->dev = &pdev->dev;
413 platform_set_drvdata(pdev, i2c);
415 spin_lock_init(&i2c->lock);
416 init_completion(&i2c->done);
418 i2c->clk = devm_clk_get(&pdev->dev, NULL);
419 if (IS_ERR(i2c->clk)) {
420 dev_err(&pdev->dev, "can't get device clock\n");
421 return PTR_ERR(i2c->clk);
424 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
425 i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
426 if (IS_ERR(i2c->regs))
427 return PTR_ERR(i2c->regs);
429 irq = platform_get_irq(pdev, 0);
431 dev_err(&pdev->dev, "can't find IRQ\n");
435 ret = devm_request_irq(&pdev->dev, irq, meson_i2c_irq, 0, NULL, i2c);
437 dev_err(&pdev->dev, "can't request IRQ\n");
441 ret = clk_prepare(i2c->clk);
443 dev_err(&pdev->dev, "can't prepare clock\n");
447 strlcpy(i2c->adap.name, "Meson I2C adapter",
448 sizeof(i2c->adap.name));
449 i2c->adap.owner = THIS_MODULE;
450 i2c->adap.algo = &meson_i2c_algorithm;
451 i2c->adap.dev.parent = &pdev->dev;
452 i2c->adap.dev.of_node = np;
453 i2c->adap.algo_data = i2c;
456 * A transfer is triggered when START bit changes from 0 to 1.
457 * Ensure that the bit is set to 0 after probe
459 meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
461 ret = i2c_add_adapter(&i2c->adap);
463 clk_unprepare(i2c->clk);
467 meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
472 static int meson_i2c_remove(struct platform_device *pdev)
474 struct meson_i2c *i2c = platform_get_drvdata(pdev);
476 i2c_del_adapter(&i2c->adap);
477 clk_unprepare(i2c->clk);
482 static const struct of_device_id meson_i2c_match[] = {
483 { .compatible = "amlogic,meson6-i2c" },
484 { .compatible = "amlogic,meson-gxbb-i2c" },
487 MODULE_DEVICE_TABLE(of, meson_i2c_match);
489 static struct platform_driver meson_i2c_driver = {
490 .probe = meson_i2c_probe,
491 .remove = meson_i2c_remove,
494 .of_match_table = meson_i2c_match,
498 module_platform_driver(meson_i2c_driver);
500 MODULE_DESCRIPTION("Amlogic Meson I2C Bus driver");
501 MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
502 MODULE_LICENSE("GPL v2");