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
27enum {
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
37struct 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
48struct meson_i2c_data {
49	unsigned char div_factor;
50};
51
52struct 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
64static 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
71static 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 */
85static 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 */
106static 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 */
128static 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
155static 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
167static 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
216static 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
231static 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
260static 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
281static const struct dm_i2c_ops meson_i2c_ops = {
282	.xfer          = meson_i2c_xfer,
283	.set_bus_speed = meson_i2c_set_bus_speed,
284};
285
286static const struct meson_i2c_data i2c_meson6_data = {
287	.div_factor = 4,
288};
289
290static const struct meson_i2c_data i2c_gxbb_data = {
291	.div_factor = 4,
292};
293
294static const struct meson_i2c_data i2c_axg_data = {
295	.div_factor = 3,
296};
297
298static 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
306U_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