1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2016 Maxime Ripard <maxime.ripard@free-electrons.com>
4  * Copyright (C) 2017 Jonathan Liu <net147@gmail.com>
5  */
6 
7 #include <linux/clk.h>
8 #include <linux/i2c.h>
9 #include <linux/iopoll.h>
10 
11 #include "sun4i_hdmi.h"
12 
13 #define SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK ( \
14 	SUN4I_HDMI_DDC_INT_STATUS_ILLEGAL_FIFO_OPERATION | \
15 	SUN4I_HDMI_DDC_INT_STATUS_DDC_RX_FIFO_UNDERFLOW | \
16 	SUN4I_HDMI_DDC_INT_STATUS_DDC_TX_FIFO_OVERFLOW | \
17 	SUN4I_HDMI_DDC_INT_STATUS_ARBITRATION_ERROR | \
18 	SUN4I_HDMI_DDC_INT_STATUS_ACK_ERROR | \
19 	SUN4I_HDMI_DDC_INT_STATUS_BUS_ERROR \
20 )
21 
22 /* FIFO request bit is set when FIFO level is above RX_THRESHOLD during read */
23 #define RX_THRESHOLD SUN4I_HDMI_DDC_FIFO_CTRL_RX_THRES_MAX
24 
25 static int fifo_transfer(struct sun4i_hdmi *hdmi, u8 *buf, int len, bool read)
26 {
27 	/*
28 	 * 1 byte takes 9 clock cycles (8 bits + 1 ACK) = 90 us for 100 kHz
29 	 * clock. As clock rate is fixed, just round it up to 100 us.
30 	 */
31 	const unsigned long byte_time_ns = 100;
32 	const u32 mask = SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK |
33 			 SUN4I_HDMI_DDC_INT_STATUS_FIFO_REQUEST |
34 			 SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE;
35 	u32 reg;
36 	/*
37 	 * If threshold is inclusive, then the FIFO may only have
38 	 * RX_THRESHOLD number of bytes, instead of RX_THRESHOLD + 1.
39 	 */
40 	int read_len = RX_THRESHOLD +
41 		(hdmi->variant->ddc_fifo_thres_incl ? 0 : 1);
42 
43 	/*
44 	 * Limit transfer length by FIFO threshold or FIFO size.
45 	 * For TX the threshold is for an empty FIFO.
46 	 */
47 	len = min_t(int, len, read ? read_len : SUN4I_HDMI_DDC_FIFO_SIZE);
48 
49 	/* Wait until error, FIFO request bit set or transfer complete */
50 	if (regmap_field_read_poll_timeout(hdmi->field_ddc_int_status, reg,
51 					   reg & mask, len * byte_time_ns,
52 					   100000))
53 		return -ETIMEDOUT;
54 
55 	if (reg & SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK)
56 		return -EIO;
57 
58 	if (read)
59 		readsb(hdmi->base + hdmi->variant->ddc_fifo_reg, buf, len);
60 	else
61 		writesb(hdmi->base + hdmi->variant->ddc_fifo_reg, buf, len);
62 
63 	/* Clear FIFO request bit by forcing a write to that bit */
64 	regmap_field_force_write(hdmi->field_ddc_int_status,
65 				 SUN4I_HDMI_DDC_INT_STATUS_FIFO_REQUEST);
66 
67 	return len;
68 }
69 
70 static int xfer_msg(struct sun4i_hdmi *hdmi, struct i2c_msg *msg)
71 {
72 	int i, len;
73 	u32 reg;
74 
75 	/* Set FIFO direction */
76 	if (hdmi->variant->ddc_fifo_has_dir) {
77 		reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
78 		reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
79 		reg |= (msg->flags & I2C_M_RD) ?
80 		       SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ :
81 		       SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE;
82 		writel(reg, hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
83 	}
84 
85 	/* Clear address register (not cleared by soft reset) */
86 	regmap_field_write(hdmi->field_ddc_addr_reg, 0);
87 
88 	/* Set I2C address */
89 	regmap_field_write(hdmi->field_ddc_slave_addr, msg->addr);
90 
91 	/*
92 	 * Set FIFO RX/TX thresholds and clear FIFO
93 	 *
94 	 * If threshold is inclusive, we can set the TX threshold to
95 	 * 0 instead of 1.
96 	 */
97 	regmap_field_write(hdmi->field_ddc_fifo_tx_thres,
98 			   hdmi->variant->ddc_fifo_thres_incl ? 0 : 1);
99 	regmap_field_write(hdmi->field_ddc_fifo_rx_thres, RX_THRESHOLD);
100 	regmap_field_write(hdmi->field_ddc_fifo_clear, 1);
101 	if (regmap_field_read_poll_timeout(hdmi->field_ddc_fifo_clear,
102 					   reg, !reg, 100, 2000))
103 		return -EIO;
104 
105 	/* Set transfer length */
106 	regmap_field_write(hdmi->field_ddc_byte_count, msg->len);
107 
108 	/* Set command */
109 	regmap_field_write(hdmi->field_ddc_cmd,
110 			   msg->flags & I2C_M_RD ?
111 			   SUN4I_HDMI_DDC_CMD_IMPLICIT_READ :
112 			   SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE);
113 
114 	/* Clear interrupt status bits by forcing a write */
115 	regmap_field_force_write(hdmi->field_ddc_int_status,
116 				 SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK |
117 				 SUN4I_HDMI_DDC_INT_STATUS_FIFO_REQUEST |
118 				 SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE);
119 
120 	/* Start command */
121 	regmap_field_write(hdmi->field_ddc_start, 1);
122 
123 	/* Transfer bytes */
124 	for (i = 0; i < msg->len; i += len) {
125 		len = fifo_transfer(hdmi, msg->buf + i, msg->len - i,
126 				    msg->flags & I2C_M_RD);
127 		if (len <= 0)
128 			return len;
129 	}
130 
131 	/* Wait for command to finish */
132 	if (regmap_field_read_poll_timeout(hdmi->field_ddc_start,
133 					   reg, !reg, 100, 100000))
134 		return -EIO;
135 
136 	/* Check for errors */
137 	regmap_field_read(hdmi->field_ddc_int_status, &reg);
138 	if ((reg & SUN4I_HDMI_DDC_INT_STATUS_ERROR_MASK) ||
139 	    !(reg & SUN4I_HDMI_DDC_INT_STATUS_TRANSFER_COMPLETE)) {
140 		return -EIO;
141 	}
142 
143 	return 0;
144 }
145 
146 static int sun4i_hdmi_i2c_xfer(struct i2c_adapter *adap,
147 			       struct i2c_msg *msgs, int num)
148 {
149 	struct sun4i_hdmi *hdmi = i2c_get_adapdata(adap);
150 	u32 reg;
151 	int err, i, ret = num;
152 
153 	for (i = 0; i < num; i++) {
154 		if (!msgs[i].len)
155 			return -EINVAL;
156 		if (msgs[i].len > SUN4I_HDMI_DDC_BYTE_COUNT_MAX)
157 			return -EINVAL;
158 	}
159 
160 	/* DDC clock needs to be enabled for the module to work */
161 	clk_prepare_enable(hdmi->ddc_clk);
162 	clk_set_rate(hdmi->ddc_clk, 100000);
163 
164 	/* Reset I2C controller */
165 	regmap_field_write(hdmi->field_ddc_en, 1);
166 	regmap_field_write(hdmi->field_ddc_reset, 1);
167 	if (regmap_field_read_poll_timeout(hdmi->field_ddc_reset,
168 					   reg, !reg, 100, 2000)) {
169 		clk_disable_unprepare(hdmi->ddc_clk);
170 		return -EIO;
171 	}
172 
173 	regmap_field_write(hdmi->field_ddc_sck_en, 1);
174 	regmap_field_write(hdmi->field_ddc_sda_en, 1);
175 
176 	for (i = 0; i < num; i++) {
177 		err = xfer_msg(hdmi, &msgs[i]);
178 		if (err) {
179 			ret = err;
180 			break;
181 		}
182 	}
183 
184 	clk_disable_unprepare(hdmi->ddc_clk);
185 	return ret;
186 }
187 
188 static u32 sun4i_hdmi_i2c_func(struct i2c_adapter *adap)
189 {
190 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
191 }
192 
193 static const struct i2c_algorithm sun4i_hdmi_i2c_algorithm = {
194 	.master_xfer	= sun4i_hdmi_i2c_xfer,
195 	.functionality	= sun4i_hdmi_i2c_func,
196 };
197 
198 static int sun4i_hdmi_init_regmap_fields(struct sun4i_hdmi *hdmi)
199 {
200 	hdmi->field_ddc_en =
201 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
202 					hdmi->variant->field_ddc_en);
203 	if (IS_ERR(hdmi->field_ddc_en))
204 		return PTR_ERR(hdmi->field_ddc_en);
205 
206 	hdmi->field_ddc_start =
207 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
208 					hdmi->variant->field_ddc_start);
209 	if (IS_ERR(hdmi->field_ddc_start))
210 		return PTR_ERR(hdmi->field_ddc_start);
211 
212 	hdmi->field_ddc_reset =
213 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
214 					hdmi->variant->field_ddc_reset);
215 	if (IS_ERR(hdmi->field_ddc_reset))
216 		return PTR_ERR(hdmi->field_ddc_reset);
217 
218 	hdmi->field_ddc_addr_reg =
219 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
220 					hdmi->variant->field_ddc_addr_reg);
221 	if (IS_ERR(hdmi->field_ddc_addr_reg))
222 		return PTR_ERR(hdmi->field_ddc_addr_reg);
223 
224 	hdmi->field_ddc_slave_addr =
225 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
226 					hdmi->variant->field_ddc_slave_addr);
227 	if (IS_ERR(hdmi->field_ddc_slave_addr))
228 		return PTR_ERR(hdmi->field_ddc_slave_addr);
229 
230 	hdmi->field_ddc_int_mask =
231 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
232 					hdmi->variant->field_ddc_int_mask);
233 	if (IS_ERR(hdmi->field_ddc_int_mask))
234 		return PTR_ERR(hdmi->field_ddc_int_mask);
235 
236 	hdmi->field_ddc_int_status =
237 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
238 					hdmi->variant->field_ddc_int_status);
239 	if (IS_ERR(hdmi->field_ddc_int_status))
240 		return PTR_ERR(hdmi->field_ddc_int_status);
241 
242 	hdmi->field_ddc_fifo_clear =
243 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
244 					hdmi->variant->field_ddc_fifo_clear);
245 	if (IS_ERR(hdmi->field_ddc_fifo_clear))
246 		return PTR_ERR(hdmi->field_ddc_fifo_clear);
247 
248 	hdmi->field_ddc_fifo_rx_thres =
249 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
250 					hdmi->variant->field_ddc_fifo_rx_thres);
251 	if (IS_ERR(hdmi->field_ddc_fifo_rx_thres))
252 		return PTR_ERR(hdmi->field_ddc_fifo_rx_thres);
253 
254 	hdmi->field_ddc_fifo_tx_thres =
255 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
256 					hdmi->variant->field_ddc_fifo_tx_thres);
257 	if (IS_ERR(hdmi->field_ddc_fifo_tx_thres))
258 		return PTR_ERR(hdmi->field_ddc_fifo_tx_thres);
259 
260 	hdmi->field_ddc_byte_count =
261 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
262 					hdmi->variant->field_ddc_byte_count);
263 	if (IS_ERR(hdmi->field_ddc_byte_count))
264 		return PTR_ERR(hdmi->field_ddc_byte_count);
265 
266 	hdmi->field_ddc_cmd =
267 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
268 					hdmi->variant->field_ddc_cmd);
269 	if (IS_ERR(hdmi->field_ddc_cmd))
270 		return PTR_ERR(hdmi->field_ddc_cmd);
271 
272 	hdmi->field_ddc_sda_en =
273 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
274 					hdmi->variant->field_ddc_sda_en);
275 	if (IS_ERR(hdmi->field_ddc_sda_en))
276 		return PTR_ERR(hdmi->field_ddc_sda_en);
277 
278 	hdmi->field_ddc_sck_en =
279 		devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
280 					hdmi->variant->field_ddc_sck_en);
281 	if (IS_ERR(hdmi->field_ddc_sck_en))
282 		return PTR_ERR(hdmi->field_ddc_sck_en);
283 
284 	return 0;
285 }
286 
287 int sun4i_hdmi_i2c_create(struct device *dev, struct sun4i_hdmi *hdmi)
288 {
289 	struct i2c_adapter *adap;
290 	int ret = 0;
291 
292 	ret = sun4i_ddc_create(hdmi, hdmi->ddc_parent_clk);
293 	if (ret)
294 		return ret;
295 
296 	ret = sun4i_hdmi_init_regmap_fields(hdmi);
297 	if (ret)
298 		return ret;
299 
300 	adap = devm_kzalloc(dev, sizeof(*adap), GFP_KERNEL);
301 	if (!adap)
302 		return -ENOMEM;
303 
304 	adap->owner = THIS_MODULE;
305 	adap->class = I2C_CLASS_DDC;
306 	adap->algo = &sun4i_hdmi_i2c_algorithm;
307 	strlcpy(adap->name, "sun4i_hdmi_i2c adapter", sizeof(adap->name));
308 	i2c_set_adapdata(adap, hdmi);
309 
310 	ret = i2c_add_adapter(adap);
311 	if (ret)
312 		return ret;
313 
314 	hdmi->i2c = adap;
315 
316 	return ret;
317 }
318