1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Designware HDMI CEC driver
4  *
5  * Copyright (C) 2015-2017 Russell King.
6  */
7 #include <linux/interrupt.h>
8 #include <linux/io.h>
9 #include <linux/module.h>
10 #include <linux/platform_device.h>
11 #include <linux/sched.h>
12 #include <linux/slab.h>
13 
14 #include <drm/drm_edid.h>
15 
16 #include <media/cec.h>
17 #include <media/cec-notifier.h>
18 
19 #include "dw-hdmi-cec.h"
20 
21 enum {
22 	HDMI_IH_CEC_STAT0	= 0x0106,
23 	HDMI_IH_MUTE_CEC_STAT0	= 0x0186,
24 
25 	HDMI_CEC_CTRL		= 0x7d00,
26 	CEC_CTRL_START		= BIT(0),
27 	CEC_CTRL_FRAME_TYP	= 3 << 1,
28 	CEC_CTRL_RETRY		= 0 << 1,
29 	CEC_CTRL_NORMAL		= 1 << 1,
30 	CEC_CTRL_IMMED		= 2 << 1,
31 
32 	HDMI_CEC_STAT		= 0x7d01,
33 	CEC_STAT_DONE		= BIT(0),
34 	CEC_STAT_EOM		= BIT(1),
35 	CEC_STAT_NACK		= BIT(2),
36 	CEC_STAT_ARBLOST	= BIT(3),
37 	CEC_STAT_ERROR_INIT	= BIT(4),
38 	CEC_STAT_ERROR_FOLL	= BIT(5),
39 	CEC_STAT_WAKEUP		= BIT(6),
40 
41 	HDMI_CEC_MASK		= 0x7d02,
42 	HDMI_CEC_POLARITY	= 0x7d03,
43 	HDMI_CEC_INT		= 0x7d04,
44 	HDMI_CEC_ADDR_L		= 0x7d05,
45 	HDMI_CEC_ADDR_H		= 0x7d06,
46 	HDMI_CEC_TX_CNT		= 0x7d07,
47 	HDMI_CEC_RX_CNT		= 0x7d08,
48 	HDMI_CEC_TX_DATA0	= 0x7d10,
49 	HDMI_CEC_RX_DATA0	= 0x7d20,
50 	HDMI_CEC_LOCK		= 0x7d30,
51 	HDMI_CEC_WKUPCTRL	= 0x7d31,
52 };
53 
54 struct dw_hdmi_cec {
55 	struct dw_hdmi *hdmi;
56 	const struct dw_hdmi_cec_ops *ops;
57 	u32 addresses;
58 	struct cec_adapter *adap;
59 	struct cec_msg rx_msg;
60 	unsigned int tx_status;
61 	bool tx_done;
62 	bool rx_done;
63 	struct cec_notifier *notify;
64 	int irq;
65 };
66 
67 static void dw_hdmi_write(struct dw_hdmi_cec *cec, u8 val, int offset)
68 {
69 	cec->ops->write(cec->hdmi, val, offset);
70 }
71 
72 static u8 dw_hdmi_read(struct dw_hdmi_cec *cec, int offset)
73 {
74 	return cec->ops->read(cec->hdmi, offset);
75 }
76 
77 static int dw_hdmi_cec_log_addr(struct cec_adapter *adap, u8 logical_addr)
78 {
79 	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
80 
81 	if (logical_addr == CEC_LOG_ADDR_INVALID)
82 		cec->addresses = 0;
83 	else
84 		cec->addresses |= BIT(logical_addr) | BIT(15);
85 
86 	dw_hdmi_write(cec, cec->addresses & 255, HDMI_CEC_ADDR_L);
87 	dw_hdmi_write(cec, cec->addresses >> 8, HDMI_CEC_ADDR_H);
88 
89 	return 0;
90 }
91 
92 static int dw_hdmi_cec_transmit(struct cec_adapter *adap, u8 attempts,
93 				u32 signal_free_time, struct cec_msg *msg)
94 {
95 	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
96 	unsigned int i, ctrl;
97 
98 	switch (signal_free_time) {
99 	case CEC_SIGNAL_FREE_TIME_RETRY:
100 		ctrl = CEC_CTRL_RETRY;
101 		break;
102 	case CEC_SIGNAL_FREE_TIME_NEW_INITIATOR:
103 	default:
104 		ctrl = CEC_CTRL_NORMAL;
105 		break;
106 	case CEC_SIGNAL_FREE_TIME_NEXT_XFER:
107 		ctrl = CEC_CTRL_IMMED;
108 		break;
109 	}
110 
111 	for (i = 0; i < msg->len; i++)
112 		dw_hdmi_write(cec, msg->msg[i], HDMI_CEC_TX_DATA0 + i);
113 
114 	dw_hdmi_write(cec, msg->len, HDMI_CEC_TX_CNT);
115 	dw_hdmi_write(cec, ctrl | CEC_CTRL_START, HDMI_CEC_CTRL);
116 
117 	return 0;
118 }
119 
120 static irqreturn_t dw_hdmi_cec_hardirq(int irq, void *data)
121 {
122 	struct cec_adapter *adap = data;
123 	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
124 	unsigned int stat = dw_hdmi_read(cec, HDMI_IH_CEC_STAT0);
125 	irqreturn_t ret = IRQ_HANDLED;
126 
127 	if (stat == 0)
128 		return IRQ_NONE;
129 
130 	dw_hdmi_write(cec, stat, HDMI_IH_CEC_STAT0);
131 
132 	if (stat & CEC_STAT_ERROR_INIT) {
133 		cec->tx_status = CEC_TX_STATUS_ERROR;
134 		cec->tx_done = true;
135 		ret = IRQ_WAKE_THREAD;
136 	} else if (stat & CEC_STAT_DONE) {
137 		cec->tx_status = CEC_TX_STATUS_OK;
138 		cec->tx_done = true;
139 		ret = IRQ_WAKE_THREAD;
140 	} else if (stat & CEC_STAT_NACK) {
141 		cec->tx_status = CEC_TX_STATUS_NACK;
142 		cec->tx_done = true;
143 		ret = IRQ_WAKE_THREAD;
144 	}
145 
146 	if (stat & CEC_STAT_EOM) {
147 		unsigned int len, i;
148 
149 		len = dw_hdmi_read(cec, HDMI_CEC_RX_CNT);
150 		if (len > sizeof(cec->rx_msg.msg))
151 			len = sizeof(cec->rx_msg.msg);
152 
153 		for (i = 0; i < len; i++)
154 			cec->rx_msg.msg[i] =
155 				dw_hdmi_read(cec, HDMI_CEC_RX_DATA0 + i);
156 
157 		dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);
158 
159 		cec->rx_msg.len = len;
160 		smp_wmb();
161 		cec->rx_done = true;
162 
163 		ret = IRQ_WAKE_THREAD;
164 	}
165 
166 	return ret;
167 }
168 
169 static irqreturn_t dw_hdmi_cec_thread(int irq, void *data)
170 {
171 	struct cec_adapter *adap = data;
172 	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
173 
174 	if (cec->tx_done) {
175 		cec->tx_done = false;
176 		cec_transmit_attempt_done(adap, cec->tx_status);
177 	}
178 	if (cec->rx_done) {
179 		cec->rx_done = false;
180 		smp_rmb();
181 		cec_received_msg(adap, &cec->rx_msg);
182 	}
183 	return IRQ_HANDLED;
184 }
185 
186 static int dw_hdmi_cec_enable(struct cec_adapter *adap, bool enable)
187 {
188 	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
189 
190 	if (!enable) {
191 		dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
192 		dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
193 		dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);
194 
195 		cec->ops->disable(cec->hdmi);
196 	} else {
197 		unsigned int irqs;
198 
199 		dw_hdmi_write(cec, 0, HDMI_CEC_CTRL);
200 		dw_hdmi_write(cec, ~0, HDMI_IH_CEC_STAT0);
201 		dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);
202 
203 		dw_hdmi_cec_log_addr(cec->adap, CEC_LOG_ADDR_INVALID);
204 
205 		cec->ops->enable(cec->hdmi);
206 
207 		irqs = CEC_STAT_ERROR_INIT | CEC_STAT_NACK | CEC_STAT_EOM |
208 		       CEC_STAT_DONE;
209 		dw_hdmi_write(cec, irqs, HDMI_CEC_POLARITY);
210 		dw_hdmi_write(cec, ~irqs, HDMI_CEC_MASK);
211 		dw_hdmi_write(cec, ~irqs, HDMI_IH_MUTE_CEC_STAT0);
212 	}
213 	return 0;
214 }
215 
216 static const struct cec_adap_ops dw_hdmi_cec_ops = {
217 	.adap_enable = dw_hdmi_cec_enable,
218 	.adap_log_addr = dw_hdmi_cec_log_addr,
219 	.adap_transmit = dw_hdmi_cec_transmit,
220 };
221 
222 static void dw_hdmi_cec_del(void *data)
223 {
224 	struct dw_hdmi_cec *cec = data;
225 
226 	cec_delete_adapter(cec->adap);
227 }
228 
229 static int dw_hdmi_cec_probe(struct platform_device *pdev)
230 {
231 	struct dw_hdmi_cec_data *data = dev_get_platdata(&pdev->dev);
232 	struct dw_hdmi_cec *cec;
233 	int ret;
234 
235 	if (!data)
236 		return -ENXIO;
237 
238 	/*
239 	 * Our device is just a convenience - we want to link to the real
240 	 * hardware device here, so that userspace can see the association
241 	 * between the HDMI hardware and its associated CEC chardev.
242 	 */
243 	cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
244 	if (!cec)
245 		return -ENOMEM;
246 
247 	cec->irq = data->irq;
248 	cec->ops = data->ops;
249 	cec->hdmi = data->hdmi;
250 
251 	platform_set_drvdata(pdev, cec);
252 
253 	dw_hdmi_write(cec, 0, HDMI_CEC_TX_CNT);
254 	dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
255 	dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
256 	dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);
257 
258 	cec->adap = cec_allocate_adapter(&dw_hdmi_cec_ops, cec, "dw_hdmi",
259 					 CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT |
260 					 CEC_CAP_RC | CEC_CAP_PASSTHROUGH,
261 					 CEC_MAX_LOG_ADDRS);
262 	if (IS_ERR(cec->adap))
263 		return PTR_ERR(cec->adap);
264 
265 	/* override the module pointer */
266 	cec->adap->owner = THIS_MODULE;
267 
268 	ret = devm_add_action(&pdev->dev, dw_hdmi_cec_del, cec);
269 	if (ret) {
270 		cec_delete_adapter(cec->adap);
271 		return ret;
272 	}
273 
274 	ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
275 					dw_hdmi_cec_hardirq,
276 					dw_hdmi_cec_thread, IRQF_SHARED,
277 					"dw-hdmi-cec", cec->adap);
278 	if (ret < 0)
279 		return ret;
280 
281 	cec->notify = cec_notifier_get(pdev->dev.parent);
282 	if (!cec->notify)
283 		return -ENOMEM;
284 
285 	ret = cec_register_adapter(cec->adap, pdev->dev.parent);
286 	if (ret < 0) {
287 		cec_notifier_put(cec->notify);
288 		return ret;
289 	}
290 
291 	/*
292 	 * CEC documentation says we must not call cec_delete_adapter
293 	 * after a successful call to cec_register_adapter().
294 	 */
295 	devm_remove_action(&pdev->dev, dw_hdmi_cec_del, cec);
296 
297 	cec_register_cec_notifier(cec->adap, cec->notify);
298 
299 	return 0;
300 }
301 
302 static int dw_hdmi_cec_remove(struct platform_device *pdev)
303 {
304 	struct dw_hdmi_cec *cec = platform_get_drvdata(pdev);
305 
306 	cec_unregister_adapter(cec->adap);
307 	cec_notifier_put(cec->notify);
308 
309 	return 0;
310 }
311 
312 static struct platform_driver dw_hdmi_cec_driver = {
313 	.probe	= dw_hdmi_cec_probe,
314 	.remove	= dw_hdmi_cec_remove,
315 	.driver = {
316 		.name = "dw-hdmi-cec",
317 	},
318 };
319 module_platform_driver(dw_hdmi_cec_driver);
320 
321 MODULE_AUTHOR("Russell King <rmk+kernel@armlinux.org.uk>");
322 MODULE_DESCRIPTION("Synopsys Designware HDMI CEC driver for i.MX");
323 MODULE_LICENSE("GPL");
324 MODULE_ALIAS(PLATFORM_MODULE_PREFIX "dw-hdmi-cec");
325