1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2014 MediaTek Inc.
4  * Author: Jie Qiu <jie.qiu@mediatek.com>
5  */
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/i2c.h>
9 #include <linux/time.h>
10 #include <linux/delay.h>
11 #include <linux/errno.h>
12 #include <linux/err.h>
13 #include <linux/platform_device.h>
14 #include <linux/clk.h>
15 #include <linux/slab.h>
16 #include <linux/io.h>
17 #include <linux/iopoll.h>
18 #include <linux/of_address.h>
19 #include <linux/of_irq.h>
20 #include <linux/of_platform.h>
21 
22 #include "mtk_drm_drv.h"
23 #include "mtk_hdmi.h"
24 
25 #define SIF1_CLOK		(288)
26 #define DDC_DDCMCTL0		(0x0)
27 #define DDCM_ODRAIN			BIT(31)
28 #define DDCM_CLK_DIV_OFFSET		(16)
29 #define DDCM_CLK_DIV_MASK		(0xfff << 16)
30 #define DDCM_CS_STATUS			BIT(4)
31 #define DDCM_SCL_STATE			BIT(3)
32 #define DDCM_SDA_STATE			BIT(2)
33 #define DDCM_SM0EN			BIT(1)
34 #define DDCM_SCL_STRECH			BIT(0)
35 #define DDC_DDCMCTL1		(0x4)
36 #define DDCM_ACK_OFFSET			(16)
37 #define DDCM_ACK_MASK			(0xff << 16)
38 #define DDCM_PGLEN_OFFSET		(8)
39 #define DDCM_PGLEN_MASK			(0x7 << 8)
40 #define DDCM_SIF_MODE_OFFSET		(4)
41 #define DDCM_SIF_MODE_MASK		(0x7 << 4)
42 #define DDCM_START			(0x1)
43 #define DDCM_WRITE_DATA			(0x2)
44 #define DDCM_STOP			(0x3)
45 #define DDCM_READ_DATA_NO_ACK		(0x4)
46 #define DDCM_READ_DATA_ACK		(0x5)
47 #define DDCM_TRI			BIT(0)
48 #define DDC_DDCMD0		(0x8)
49 #define DDCM_DATA3			(0xff << 24)
50 #define DDCM_DATA2			(0xff << 16)
51 #define DDCM_DATA1			(0xff << 8)
52 #define DDCM_DATA0			(0xff << 0)
53 #define DDC_DDCMD1		(0xc)
54 #define DDCM_DATA7			(0xff << 24)
55 #define DDCM_DATA6			(0xff << 16)
56 #define DDCM_DATA5			(0xff << 8)
57 #define DDCM_DATA4			(0xff << 0)
58 
59 struct mtk_hdmi_ddc {
60 	struct i2c_adapter adap;
61 	struct clk *clk;
62 	void __iomem *regs;
63 };
64 
65 static inline void sif_set_bit(struct mtk_hdmi_ddc *ddc, unsigned int offset,
66 			       unsigned int val)
67 {
68 	writel(readl(ddc->regs + offset) | val, ddc->regs + offset);
69 }
70 
71 static inline void sif_clr_bit(struct mtk_hdmi_ddc *ddc, unsigned int offset,
72 			       unsigned int val)
73 {
74 	writel(readl(ddc->regs + offset) & ~val, ddc->regs + offset);
75 }
76 
77 static inline bool sif_bit_is_set(struct mtk_hdmi_ddc *ddc, unsigned int offset,
78 				  unsigned int val)
79 {
80 	return (readl(ddc->regs + offset) & val) == val;
81 }
82 
83 static inline void sif_write_mask(struct mtk_hdmi_ddc *ddc, unsigned int offset,
84 				  unsigned int mask, unsigned int shift,
85 				  unsigned int val)
86 {
87 	unsigned int tmp;
88 
89 	tmp = readl(ddc->regs + offset);
90 	tmp &= ~mask;
91 	tmp |= (val << shift) & mask;
92 	writel(tmp, ddc->regs + offset);
93 }
94 
95 static inline unsigned int sif_read_mask(struct mtk_hdmi_ddc *ddc,
96 					 unsigned int offset, unsigned int mask,
97 					 unsigned int shift)
98 {
99 	return (readl(ddc->regs + offset) & mask) >> shift;
100 }
101 
102 static void ddcm_trigger_mode(struct mtk_hdmi_ddc *ddc, int mode)
103 {
104 	u32 val;
105 
106 	sif_write_mask(ddc, DDC_DDCMCTL1, DDCM_SIF_MODE_MASK,
107 		       DDCM_SIF_MODE_OFFSET, mode);
108 	sif_set_bit(ddc, DDC_DDCMCTL1, DDCM_TRI);
109 	readl_poll_timeout(ddc->regs + DDC_DDCMCTL1, val,
110 			   (val & DDCM_TRI) != DDCM_TRI, 4, 20000);
111 }
112 
113 static int mtk_hdmi_ddc_read_msg(struct mtk_hdmi_ddc *ddc, struct i2c_msg *msg)
114 {
115 	struct device *dev = ddc->adap.dev.parent;
116 	u32 remain_count, ack_count, ack_final, read_count, temp_count;
117 	u32 index = 0;
118 	u32 ack;
119 	int i;
120 
121 	ddcm_trigger_mode(ddc, DDCM_START);
122 	sif_write_mask(ddc, DDC_DDCMD0, 0xff, 0, (msg->addr << 1) | 0x01);
123 	sif_write_mask(ddc, DDC_DDCMCTL1, DDCM_PGLEN_MASK, DDCM_PGLEN_OFFSET,
124 		       0x00);
125 	ddcm_trigger_mode(ddc, DDCM_WRITE_DATA);
126 	ack = sif_read_mask(ddc, DDC_DDCMCTL1, DDCM_ACK_MASK, DDCM_ACK_OFFSET);
127 	dev_dbg(dev, "ack = 0x%x\n", ack);
128 	if (ack != 0x01) {
129 		dev_err(dev, "i2c ack err!\n");
130 		return -ENXIO;
131 	}
132 
133 	remain_count = msg->len;
134 	ack_count = (msg->len - 1) / 8;
135 	ack_final = 0;
136 
137 	while (remain_count > 0) {
138 		if (ack_count > 0) {
139 			read_count = 8;
140 			ack_final = 0;
141 			ack_count--;
142 		} else {
143 			read_count = remain_count;
144 			ack_final = 1;
145 		}
146 
147 		sif_write_mask(ddc, DDC_DDCMCTL1, DDCM_PGLEN_MASK,
148 			       DDCM_PGLEN_OFFSET, read_count - 1);
149 		ddcm_trigger_mode(ddc, (ack_final == 1) ?
150 				  DDCM_READ_DATA_NO_ACK :
151 				  DDCM_READ_DATA_ACK);
152 
153 		ack = sif_read_mask(ddc, DDC_DDCMCTL1, DDCM_ACK_MASK,
154 				    DDCM_ACK_OFFSET);
155 		temp_count = 0;
156 		while (((ack & (1 << temp_count)) != 0) && (temp_count < 8))
157 			temp_count++;
158 		if (((ack_final == 1) && (temp_count != (read_count - 1))) ||
159 		    ((ack_final == 0) && (temp_count != read_count))) {
160 			dev_err(dev, "Address NACK! ACK(0x%x)\n", ack);
161 			break;
162 		}
163 
164 		for (i = read_count; i >= 1; i--) {
165 			int shift;
166 			int offset;
167 
168 			if (i > 4) {
169 				offset = DDC_DDCMD1;
170 				shift = (i - 5) * 8;
171 			} else {
172 				offset = DDC_DDCMD0;
173 				shift = (i - 1) * 8;
174 			}
175 
176 			msg->buf[index + i - 1] = sif_read_mask(ddc, offset,
177 								0xff << shift,
178 								shift);
179 		}
180 
181 		remain_count -= read_count;
182 		index += read_count;
183 	}
184 
185 	return 0;
186 }
187 
188 static int mtk_hdmi_ddc_write_msg(struct mtk_hdmi_ddc *ddc, struct i2c_msg *msg)
189 {
190 	struct device *dev = ddc->adap.dev.parent;
191 	u32 ack;
192 
193 	ddcm_trigger_mode(ddc, DDCM_START);
194 	sif_write_mask(ddc, DDC_DDCMD0, DDCM_DATA0, 0, msg->addr << 1);
195 	sif_write_mask(ddc, DDC_DDCMD0, DDCM_DATA1, 8, msg->buf[0]);
196 	sif_write_mask(ddc, DDC_DDCMCTL1, DDCM_PGLEN_MASK, DDCM_PGLEN_OFFSET,
197 		       0x1);
198 	ddcm_trigger_mode(ddc, DDCM_WRITE_DATA);
199 
200 	ack = sif_read_mask(ddc, DDC_DDCMCTL1, DDCM_ACK_MASK, DDCM_ACK_OFFSET);
201 	dev_dbg(dev, "ack = %d\n", ack);
202 
203 	if (ack != 0x03) {
204 		dev_err(dev, "i2c ack err!\n");
205 		return -EIO;
206 	}
207 
208 	return 0;
209 }
210 
211 static int mtk_hdmi_ddc_xfer(struct i2c_adapter *adapter,
212 			     struct i2c_msg *msgs, int num)
213 {
214 	struct mtk_hdmi_ddc *ddc = adapter->algo_data;
215 	struct device *dev = adapter->dev.parent;
216 	int ret;
217 	int i;
218 
219 	if (!ddc) {
220 		dev_err(dev, "invalid arguments\n");
221 		return -EINVAL;
222 	}
223 
224 	sif_set_bit(ddc, DDC_DDCMCTL0, DDCM_SCL_STRECH);
225 	sif_set_bit(ddc, DDC_DDCMCTL0, DDCM_SM0EN);
226 	sif_clr_bit(ddc, DDC_DDCMCTL0, DDCM_ODRAIN);
227 
228 	if (sif_bit_is_set(ddc, DDC_DDCMCTL1, DDCM_TRI)) {
229 		dev_err(dev, "ddc line is busy!\n");
230 		return -EBUSY;
231 	}
232 
233 	sif_write_mask(ddc, DDC_DDCMCTL0, DDCM_CLK_DIV_MASK,
234 		       DDCM_CLK_DIV_OFFSET, SIF1_CLOK);
235 
236 	for (i = 0; i < num; i++) {
237 		struct i2c_msg *msg = &msgs[i];
238 
239 		dev_dbg(dev, "i2c msg, adr:0x%x, flags:%d, len :0x%x\n",
240 			msg->addr, msg->flags, msg->len);
241 
242 		if (msg->flags & I2C_M_RD)
243 			ret = mtk_hdmi_ddc_read_msg(ddc, msg);
244 		else
245 			ret = mtk_hdmi_ddc_write_msg(ddc, msg);
246 		if (ret < 0)
247 			goto xfer_end;
248 	}
249 
250 	ddcm_trigger_mode(ddc, DDCM_STOP);
251 
252 	return i;
253 
254 xfer_end:
255 	ddcm_trigger_mode(ddc, DDCM_STOP);
256 	dev_err(dev, "ddc failed!\n");
257 	return ret;
258 }
259 
260 static u32 mtk_hdmi_ddc_func(struct i2c_adapter *adapter)
261 {
262 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
263 }
264 
265 static const struct i2c_algorithm mtk_hdmi_ddc_algorithm = {
266 	.master_xfer = mtk_hdmi_ddc_xfer,
267 	.functionality = mtk_hdmi_ddc_func,
268 };
269 
270 static int mtk_hdmi_ddc_probe(struct platform_device *pdev)
271 {
272 	struct device *dev = &pdev->dev;
273 	struct mtk_hdmi_ddc *ddc;
274 	struct resource *mem;
275 	int ret;
276 
277 	ddc = devm_kzalloc(dev, sizeof(struct mtk_hdmi_ddc), GFP_KERNEL);
278 	if (!ddc)
279 		return -ENOMEM;
280 
281 	ddc->clk = devm_clk_get(dev, "ddc-i2c");
282 	if (IS_ERR(ddc->clk)) {
283 		dev_err(dev, "get ddc_clk failed: %p ,\n", ddc->clk);
284 		return PTR_ERR(ddc->clk);
285 	}
286 
287 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
288 	ddc->regs = devm_ioremap_resource(&pdev->dev, mem);
289 	if (IS_ERR(ddc->regs))
290 		return PTR_ERR(ddc->regs);
291 
292 	ret = clk_prepare_enable(ddc->clk);
293 	if (ret) {
294 		dev_err(dev, "enable ddc clk failed!\n");
295 		return ret;
296 	}
297 
298 	strscpy(ddc->adap.name, "mediatek-hdmi-ddc", sizeof(ddc->adap.name));
299 	ddc->adap.owner = THIS_MODULE;
300 	ddc->adap.class = I2C_CLASS_DDC;
301 	ddc->adap.algo = &mtk_hdmi_ddc_algorithm;
302 	ddc->adap.retries = 3;
303 	ddc->adap.dev.of_node = dev->of_node;
304 	ddc->adap.algo_data = ddc;
305 	ddc->adap.dev.parent = &pdev->dev;
306 
307 	ret = i2c_add_adapter(&ddc->adap);
308 	if (ret < 0) {
309 		dev_err(dev, "failed to add bus to i2c core\n");
310 		goto err_clk_disable;
311 	}
312 
313 	platform_set_drvdata(pdev, ddc);
314 
315 	dev_dbg(dev, "ddc->adap: %p\n", &ddc->adap);
316 	dev_dbg(dev, "ddc->clk: %p\n", ddc->clk);
317 	dev_dbg(dev, "physical adr: %pa, end: %pa\n", &mem->start,
318 		&mem->end);
319 
320 	return 0;
321 
322 err_clk_disable:
323 	clk_disable_unprepare(ddc->clk);
324 	return ret;
325 }
326 
327 static int mtk_hdmi_ddc_remove(struct platform_device *pdev)
328 {
329 	struct mtk_hdmi_ddc *ddc = platform_get_drvdata(pdev);
330 
331 	i2c_del_adapter(&ddc->adap);
332 	clk_disable_unprepare(ddc->clk);
333 
334 	return 0;
335 }
336 
337 static const struct of_device_id mtk_hdmi_ddc_match[] = {
338 	{ .compatible = "mediatek,mt8173-hdmi-ddc", },
339 	{},
340 };
341 MODULE_DEVICE_TABLE(of, mtk_hdmi_ddc_match);
342 
343 struct platform_driver mtk_hdmi_ddc_driver = {
344 	.probe = mtk_hdmi_ddc_probe,
345 	.remove = mtk_hdmi_ddc_remove,
346 	.driver = {
347 		.name = "mediatek-hdmi-ddc",
348 		.of_match_table = mtk_hdmi_ddc_match,
349 	},
350 };
351 
352 MODULE_AUTHOR("Jie Qiu <jie.qiu@mediatek.com>");
353 MODULE_DESCRIPTION("MediaTek HDMI DDC Driver");
354 MODULE_LICENSE("GPL v2");
355