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