xref: /openbmc/linux/drivers/gpu/drm/msm/hdmi/hdmi_i2c.c (revision caab277b)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2013 Red Hat
4  * Author: Rob Clark <robdclark@gmail.com>
5  */
6 
7 #include "hdmi.h"
8 
9 struct hdmi_i2c_adapter {
10 	struct i2c_adapter base;
11 	struct hdmi *hdmi;
12 	bool sw_done;
13 	wait_queue_head_t ddc_event;
14 };
15 #define to_hdmi_i2c_adapter(x) container_of(x, struct hdmi_i2c_adapter, base)
16 
init_ddc(struct hdmi_i2c_adapter * hdmi_i2c)17 static void init_ddc(struct hdmi_i2c_adapter *hdmi_i2c)
18 {
19 	struct hdmi *hdmi = hdmi_i2c->hdmi;
20 
21 	hdmi_write(hdmi, REG_HDMI_DDC_CTRL,
22 			HDMI_DDC_CTRL_SW_STATUS_RESET);
23 	hdmi_write(hdmi, REG_HDMI_DDC_CTRL,
24 			HDMI_DDC_CTRL_SOFT_RESET);
25 
26 	hdmi_write(hdmi, REG_HDMI_DDC_SPEED,
27 			HDMI_DDC_SPEED_THRESHOLD(2) |
28 			HDMI_DDC_SPEED_PRESCALE(10));
29 
30 	hdmi_write(hdmi, REG_HDMI_DDC_SETUP,
31 			HDMI_DDC_SETUP_TIMEOUT(0xff));
32 
33 	/* enable reference timer for 27us */
34 	hdmi_write(hdmi, REG_HDMI_DDC_REF,
35 			HDMI_DDC_REF_REFTIMER_ENABLE |
36 			HDMI_DDC_REF_REFTIMER(27));
37 }
38 
ddc_clear_irq(struct hdmi_i2c_adapter * hdmi_i2c)39 static int ddc_clear_irq(struct hdmi_i2c_adapter *hdmi_i2c)
40 {
41 	struct hdmi *hdmi = hdmi_i2c->hdmi;
42 	struct drm_device *dev = hdmi->dev;
43 	uint32_t retry = 0xffff;
44 	uint32_t ddc_int_ctrl;
45 
46 	do {
47 		--retry;
48 
49 		hdmi_write(hdmi, REG_HDMI_DDC_INT_CTRL,
50 				HDMI_DDC_INT_CTRL_SW_DONE_ACK |
51 				HDMI_DDC_INT_CTRL_SW_DONE_MASK);
52 
53 		ddc_int_ctrl = hdmi_read(hdmi, REG_HDMI_DDC_INT_CTRL);
54 
55 	} while ((ddc_int_ctrl & HDMI_DDC_INT_CTRL_SW_DONE_INT) && retry);
56 
57 	if (!retry) {
58 		DRM_DEV_ERROR(dev->dev, "timeout waiting for DDC\n");
59 		return -ETIMEDOUT;
60 	}
61 
62 	hdmi_i2c->sw_done = false;
63 
64 	return 0;
65 }
66 
67 #define MAX_TRANSACTIONS 4
68 
sw_done(struct hdmi_i2c_adapter * hdmi_i2c)69 static bool sw_done(struct hdmi_i2c_adapter *hdmi_i2c)
70 {
71 	struct hdmi *hdmi = hdmi_i2c->hdmi;
72 
73 	if (!hdmi_i2c->sw_done) {
74 		uint32_t ddc_int_ctrl;
75 
76 		ddc_int_ctrl = hdmi_read(hdmi, REG_HDMI_DDC_INT_CTRL);
77 
78 		if ((ddc_int_ctrl & HDMI_DDC_INT_CTRL_SW_DONE_MASK) &&
79 				(ddc_int_ctrl & HDMI_DDC_INT_CTRL_SW_DONE_INT)) {
80 			hdmi_i2c->sw_done = true;
81 			hdmi_write(hdmi, REG_HDMI_DDC_INT_CTRL,
82 					HDMI_DDC_INT_CTRL_SW_DONE_ACK);
83 		}
84 	}
85 
86 	return hdmi_i2c->sw_done;
87 }
88 
msm_hdmi_i2c_xfer(struct i2c_adapter * i2c,struct i2c_msg * msgs,int num)89 static int msm_hdmi_i2c_xfer(struct i2c_adapter *i2c,
90 		struct i2c_msg *msgs, int num)
91 {
92 	struct hdmi_i2c_adapter *hdmi_i2c = to_hdmi_i2c_adapter(i2c);
93 	struct hdmi *hdmi = hdmi_i2c->hdmi;
94 	struct drm_device *dev = hdmi->dev;
95 	static const uint32_t nack[] = {
96 			HDMI_DDC_SW_STATUS_NACK0, HDMI_DDC_SW_STATUS_NACK1,
97 			HDMI_DDC_SW_STATUS_NACK2, HDMI_DDC_SW_STATUS_NACK3,
98 	};
99 	int indices[MAX_TRANSACTIONS];
100 	int ret, i, j, index = 0;
101 	uint32_t ddc_status, ddc_data, i2c_trans;
102 
103 	num = min(num, MAX_TRANSACTIONS);
104 
105 	WARN_ON(!(hdmi_read(hdmi, REG_HDMI_CTRL) & HDMI_CTRL_ENABLE));
106 
107 	if (num == 0)
108 		return num;
109 
110 	init_ddc(hdmi_i2c);
111 
112 	ret = ddc_clear_irq(hdmi_i2c);
113 	if (ret)
114 		return ret;
115 
116 	for (i = 0; i < num; i++) {
117 		struct i2c_msg *p = &msgs[i];
118 		uint32_t raw_addr = p->addr << 1;
119 
120 		if (p->flags & I2C_M_RD)
121 			raw_addr |= 1;
122 
123 		ddc_data = HDMI_DDC_DATA_DATA(raw_addr) |
124 				HDMI_DDC_DATA_DATA_RW(DDC_WRITE);
125 
126 		if (i == 0) {
127 			ddc_data |= HDMI_DDC_DATA_INDEX(0) |
128 					HDMI_DDC_DATA_INDEX_WRITE;
129 		}
130 
131 		hdmi_write(hdmi, REG_HDMI_DDC_DATA, ddc_data);
132 		index++;
133 
134 		indices[i] = index;
135 
136 		if (p->flags & I2C_M_RD) {
137 			index += p->len;
138 		} else {
139 			for (j = 0; j < p->len; j++) {
140 				ddc_data = HDMI_DDC_DATA_DATA(p->buf[j]) |
141 						HDMI_DDC_DATA_DATA_RW(DDC_WRITE);
142 				hdmi_write(hdmi, REG_HDMI_DDC_DATA, ddc_data);
143 				index++;
144 			}
145 		}
146 
147 		i2c_trans = HDMI_I2C_TRANSACTION_REG_CNT(p->len) |
148 				HDMI_I2C_TRANSACTION_REG_RW(
149 						(p->flags & I2C_M_RD) ? DDC_READ : DDC_WRITE) |
150 				HDMI_I2C_TRANSACTION_REG_START;
151 
152 		if (i == (num - 1))
153 			i2c_trans |= HDMI_I2C_TRANSACTION_REG_STOP;
154 
155 		hdmi_write(hdmi, REG_HDMI_I2C_TRANSACTION(i), i2c_trans);
156 	}
157 
158 	/* trigger the transfer: */
159 	hdmi_write(hdmi, REG_HDMI_DDC_CTRL,
160 			HDMI_DDC_CTRL_TRANSACTION_CNT(num - 1) |
161 			HDMI_DDC_CTRL_GO);
162 
163 	ret = wait_event_timeout(hdmi_i2c->ddc_event, sw_done(hdmi_i2c), HZ/4);
164 	if (ret <= 0) {
165 		if (ret == 0)
166 			ret = -ETIMEDOUT;
167 		dev_warn(dev->dev, "DDC timeout: %d\n", ret);
168 		DBG("sw_status=%08x, hw_status=%08x, int_ctrl=%08x",
169 				hdmi_read(hdmi, REG_HDMI_DDC_SW_STATUS),
170 				hdmi_read(hdmi, REG_HDMI_DDC_HW_STATUS),
171 				hdmi_read(hdmi, REG_HDMI_DDC_INT_CTRL));
172 		return ret;
173 	}
174 
175 	ddc_status = hdmi_read(hdmi, REG_HDMI_DDC_SW_STATUS);
176 
177 	/* read back results of any read transactions: */
178 	for (i = 0; i < num; i++) {
179 		struct i2c_msg *p = &msgs[i];
180 
181 		if (!(p->flags & I2C_M_RD))
182 			continue;
183 
184 		/* check for NACK: */
185 		if (ddc_status & nack[i]) {
186 			DBG("ddc_status=%08x", ddc_status);
187 			break;
188 		}
189 
190 		ddc_data = HDMI_DDC_DATA_DATA_RW(DDC_READ) |
191 				HDMI_DDC_DATA_INDEX(indices[i]) |
192 				HDMI_DDC_DATA_INDEX_WRITE;
193 
194 		hdmi_write(hdmi, REG_HDMI_DDC_DATA, ddc_data);
195 
196 		/* discard first byte: */
197 		hdmi_read(hdmi, REG_HDMI_DDC_DATA);
198 
199 		for (j = 0; j < p->len; j++) {
200 			ddc_data = hdmi_read(hdmi, REG_HDMI_DDC_DATA);
201 			p->buf[j] = FIELD(ddc_data, HDMI_DDC_DATA_DATA);
202 		}
203 	}
204 
205 	return i;
206 }
207 
msm_hdmi_i2c_func(struct i2c_adapter * adapter)208 static u32 msm_hdmi_i2c_func(struct i2c_adapter *adapter)
209 {
210 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
211 }
212 
213 static const struct i2c_algorithm msm_hdmi_i2c_algorithm = {
214 	.master_xfer	= msm_hdmi_i2c_xfer,
215 	.functionality	= msm_hdmi_i2c_func,
216 };
217 
msm_hdmi_i2c_irq(struct i2c_adapter * i2c)218 void msm_hdmi_i2c_irq(struct i2c_adapter *i2c)
219 {
220 	struct hdmi_i2c_adapter *hdmi_i2c = to_hdmi_i2c_adapter(i2c);
221 
222 	if (sw_done(hdmi_i2c))
223 		wake_up_all(&hdmi_i2c->ddc_event);
224 }
225 
msm_hdmi_i2c_destroy(struct i2c_adapter * i2c)226 void msm_hdmi_i2c_destroy(struct i2c_adapter *i2c)
227 {
228 	struct hdmi_i2c_adapter *hdmi_i2c = to_hdmi_i2c_adapter(i2c);
229 	i2c_del_adapter(i2c);
230 	kfree(hdmi_i2c);
231 }
232 
msm_hdmi_i2c_init(struct hdmi * hdmi)233 struct i2c_adapter *msm_hdmi_i2c_init(struct hdmi *hdmi)
234 {
235 	struct hdmi_i2c_adapter *hdmi_i2c;
236 	struct i2c_adapter *i2c = NULL;
237 	int ret;
238 
239 	hdmi_i2c = kzalloc(sizeof(*hdmi_i2c), GFP_KERNEL);
240 	if (!hdmi_i2c) {
241 		ret = -ENOMEM;
242 		goto fail;
243 	}
244 
245 	i2c = &hdmi_i2c->base;
246 
247 	hdmi_i2c->hdmi = hdmi;
248 	init_waitqueue_head(&hdmi_i2c->ddc_event);
249 
250 
251 	i2c->owner = THIS_MODULE;
252 	i2c->class = I2C_CLASS_DDC;
253 	snprintf(i2c->name, sizeof(i2c->name), "msm hdmi i2c");
254 	i2c->dev.parent = &hdmi->pdev->dev;
255 	i2c->algo = &msm_hdmi_i2c_algorithm;
256 
257 	ret = i2c_add_adapter(i2c);
258 	if (ret)
259 		goto fail;
260 
261 	return i2c;
262 
263 fail:
264 	if (i2c)
265 		msm_hdmi_i2c_destroy(i2c);
266 	return ERR_PTR(ret);
267 }
268