1/*
  2 * Designware HDMI CEC driver
  3 *
  4 * Copyright (C) 2015-2017 Russell King.
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2 as
  8 * published by the Free Software Foundation.
  9 */
 10#include <linux/interrupt.h>
 11#include <linux/io.h>
 12#include <linux/module.h>
 13#include <linux/platform_device.h>
 14#include <linux/sched.h>
 15#include <linux/slab.h>
 16
 17#include <drm/drm_edid.h>
 18
 19#include <media/cec.h>
 20#include <media/cec-notifier.h>
 21
 22#include "dw-hdmi-cec.h"
 23
 24enum {
 25	HDMI_IH_CEC_STAT0	= 0x0106,
 26	HDMI_IH_MUTE_CEC_STAT0	= 0x0186,
 27
 28	HDMI_CEC_CTRL		= 0x7d00,
 29	CEC_CTRL_START		= BIT(0),
 30	CEC_CTRL_FRAME_TYP	= 3 << 1,
 31	CEC_CTRL_RETRY		= 0 << 1,
 32	CEC_CTRL_NORMAL		= 1 << 1,
 33	CEC_CTRL_IMMED		= 2 << 1,
 34
 35	HDMI_CEC_STAT		= 0x7d01,
 36	CEC_STAT_DONE		= BIT(0),
 37	CEC_STAT_EOM		= BIT(1),
 38	CEC_STAT_NACK		= BIT(2),
 39	CEC_STAT_ARBLOST	= BIT(3),
 40	CEC_STAT_ERROR_INIT	= BIT(4),
 41	CEC_STAT_ERROR_FOLL	= BIT(5),
 42	CEC_STAT_WAKEUP		= BIT(6),
 43
 44	HDMI_CEC_MASK		= 0x7d02,
 45	HDMI_CEC_POLARITY	= 0x7d03,
 46	HDMI_CEC_INT		= 0x7d04,
 47	HDMI_CEC_ADDR_L		= 0x7d05,
 48	HDMI_CEC_ADDR_H		= 0x7d06,
 49	HDMI_CEC_TX_CNT		= 0x7d07,
 50	HDMI_CEC_RX_CNT		= 0x7d08,
 51	HDMI_CEC_TX_DATA0	= 0x7d10,
 52	HDMI_CEC_RX_DATA0	= 0x7d20,
 53	HDMI_CEC_LOCK		= 0x7d30,
 54	HDMI_CEC_WKUPCTRL	= 0x7d31,
 55};
 56
 57struct dw_hdmi_cec {
 58	struct dw_hdmi *hdmi;
 59	const struct dw_hdmi_cec_ops *ops;
 60	u32 addresses;
 61	struct cec_adapter *adap;
 62	struct cec_msg rx_msg;
 63	unsigned int tx_status;
 64	bool tx_done;
 65	bool rx_done;
 66	struct cec_notifier *notify;
 67	int irq;
 68};
 69
 70static void dw_hdmi_write(struct dw_hdmi_cec *cec, u8 val, int offset)
 71{
 72	cec->ops->write(cec->hdmi, val, offset);
 73}
 74
 75static u8 dw_hdmi_read(struct dw_hdmi_cec *cec, int offset)
 76{
 77	return cec->ops->read(cec->hdmi, offset);
 78}
 79
 80static int dw_hdmi_cec_log_addr(struct cec_adapter *adap, u8 logical_addr)
 81{
 82	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
 83
 84	if (logical_addr == CEC_LOG_ADDR_INVALID)
 85		cec->addresses = 0;
 86	else
 87		cec->addresses |= BIT(logical_addr) | BIT(15);
 88
 89	dw_hdmi_write(cec, cec->addresses & 255, HDMI_CEC_ADDR_L);
 90	dw_hdmi_write(cec, cec->addresses >> 8, HDMI_CEC_ADDR_H);
 91
 92	return 0;
 93}
 94
 95static int dw_hdmi_cec_transmit(struct cec_adapter *adap, u8 attempts,
 96				u32 signal_free_time, struct cec_msg *msg)
 97{
 98	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
 99	unsigned int i, ctrl;
100
101	switch (signal_free_time) {
102	case CEC_SIGNAL_FREE_TIME_RETRY:
103		ctrl = CEC_CTRL_RETRY;
104		break;
105	case CEC_SIGNAL_FREE_TIME_NEW_INITIATOR:
106	default:
107		ctrl = CEC_CTRL_NORMAL;
108		break;
109	case CEC_SIGNAL_FREE_TIME_NEXT_XFER:
110		ctrl = CEC_CTRL_IMMED;
111		break;
112	}
113
114	for (i = 0; i < msg->len; i++)
115		dw_hdmi_write(cec, msg->msg[i], HDMI_CEC_TX_DATA0 + i);
116
117	dw_hdmi_write(cec, msg->len, HDMI_CEC_TX_CNT);
118	dw_hdmi_write(cec, ctrl | CEC_CTRL_START, HDMI_CEC_CTRL);
119
120	return 0;
121}
122
123static irqreturn_t dw_hdmi_cec_hardirq(int irq, void *data)
124{
125	struct cec_adapter *adap = data;
126	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
127	unsigned int stat = dw_hdmi_read(cec, HDMI_IH_CEC_STAT0);
128	irqreturn_t ret = IRQ_HANDLED;
129
130	if (stat == 0)
131		return IRQ_NONE;
132
133	dw_hdmi_write(cec, stat, HDMI_IH_CEC_STAT0);
134
135	if (stat & CEC_STAT_ERROR_INIT) {
136		cec->tx_status = CEC_TX_STATUS_ERROR;
137		cec->tx_done = true;
138		ret = IRQ_WAKE_THREAD;
139	} else if (stat & CEC_STAT_DONE) {
140		cec->tx_status = CEC_TX_STATUS_OK;
141		cec->tx_done = true;
142		ret = IRQ_WAKE_THREAD;
143	} else if (stat & CEC_STAT_NACK) {
144		cec->tx_status = CEC_TX_STATUS_NACK;
145		cec->tx_done = true;
146		ret = IRQ_WAKE_THREAD;
147	}
148
149	if (stat & CEC_STAT_EOM) {
150		unsigned int len, i;
151
152		len = dw_hdmi_read(cec, HDMI_CEC_RX_CNT);
153		if (len > sizeof(cec->rx_msg.msg))
154			len = sizeof(cec->rx_msg.msg);
155
156		for (i = 0; i < len; i++)
157			cec->rx_msg.msg[i] =
158				dw_hdmi_read(cec, HDMI_CEC_RX_DATA0 + i);
159
160		dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);
161
162		cec->rx_msg.len = len;
163		smp_wmb();
164		cec->rx_done = true;
165
166		ret = IRQ_WAKE_THREAD;
167	}
168
169	return ret;
170}
171
172static irqreturn_t dw_hdmi_cec_thread(int irq, void *data)
173{
174	struct cec_adapter *adap = data;
175	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
176
177	if (cec->tx_done) {
178		cec->tx_done = false;
179		cec_transmit_attempt_done(adap, cec->tx_status);
180	}
181	if (cec->rx_done) {
182		cec->rx_done = false;
183		smp_rmb();
184		cec_received_msg(adap, &cec->rx_msg);
185	}
186	return IRQ_HANDLED;
187}
188
189static int dw_hdmi_cec_enable(struct cec_adapter *adap, bool enable)
190{
191	struct dw_hdmi_cec *cec = cec_get_drvdata(adap);
192
193	if (!enable) {
194		dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
195		dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
196		dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);
197
198		cec->ops->disable(cec->hdmi);
199	} else {
200		unsigned int irqs;
201
202		dw_hdmi_write(cec, 0, HDMI_CEC_CTRL);
203		dw_hdmi_write(cec, ~0, HDMI_IH_CEC_STAT0);
204		dw_hdmi_write(cec, 0, HDMI_CEC_LOCK);
205
206		dw_hdmi_cec_log_addr(cec->adap, CEC_LOG_ADDR_INVALID);
207
208		cec->ops->enable(cec->hdmi);
209
210		irqs = CEC_STAT_ERROR_INIT | CEC_STAT_NACK | CEC_STAT_EOM |
211		       CEC_STAT_DONE;
212		dw_hdmi_write(cec, irqs, HDMI_CEC_POLARITY);
213		dw_hdmi_write(cec, ~irqs, HDMI_CEC_MASK);
214		dw_hdmi_write(cec, ~irqs, HDMI_IH_MUTE_CEC_STAT0);
215	}
216	return 0;
217}
218
219static const struct cec_adap_ops dw_hdmi_cec_ops = {
220	.adap_enable = dw_hdmi_cec_enable,
221	.adap_log_addr = dw_hdmi_cec_log_addr,
222	.adap_transmit = dw_hdmi_cec_transmit,
223};
224
225static void dw_hdmi_cec_del(void *data)
226{
227	struct dw_hdmi_cec *cec = data;
228
229	cec_delete_adapter(cec->adap);
230}
231
232static int dw_hdmi_cec_probe(struct platform_device *pdev)
233{
234	struct dw_hdmi_cec_data *data = dev_get_platdata(&pdev->dev);
235	struct dw_hdmi_cec *cec;
236	int ret;
237
238	if (!data)
239		return -ENXIO;
240
241	/*
242	 * Our device is just a convenience - we want to link to the real
243	 * hardware device here, so that userspace can see the association
244	 * between the HDMI hardware and its associated CEC chardev.
245	 */
246	cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
247	if (!cec)
248		return -ENOMEM;
249
250	cec->irq = data->irq;
251	cec->ops = data->ops;
252	cec->hdmi = data->hdmi;
253
254	platform_set_drvdata(pdev, cec);
255
256	dw_hdmi_write(cec, 0, HDMI_CEC_TX_CNT);
257	dw_hdmi_write(cec, ~0, HDMI_CEC_MASK);
258	dw_hdmi_write(cec, ~0, HDMI_IH_MUTE_CEC_STAT0);
259	dw_hdmi_write(cec, 0, HDMI_CEC_POLARITY);
260
261	cec->adap = cec_allocate_adapter(&dw_hdmi_cec_ops, cec, "dw_hdmi",
262					 CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT |
263					 CEC_CAP_RC | CEC_CAP_PASSTHROUGH,
264					 CEC_MAX_LOG_ADDRS);
265	if (IS_ERR(cec->adap))
266		return PTR_ERR(cec->adap);
267
268	/* override the module pointer */
269	cec->adap->owner = THIS_MODULE;
270
271	ret = devm_add_action(&pdev->dev, dw_hdmi_cec_del, cec);
272	if (ret) {
273		cec_delete_adapter(cec->adap);
274		return ret;
275	}
276
277	ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
278					dw_hdmi_cec_hardirq,
279					dw_hdmi_cec_thread, IRQF_SHARED,
280					"dw-hdmi-cec", cec->adap);
281	if (ret < 0)
282		return ret;
283
284	cec->notify = cec_notifier_get(pdev->dev.parent);
285	if (!cec->notify)
286		return -ENOMEM;
287
288	ret = cec_register_adapter(cec->adap, pdev->dev.parent);
289	if (ret < 0) {
290		cec_notifier_put(cec->notify);
291		return ret;
292	}
293
294	/*
295	 * CEC documentation says we must not call cec_delete_adapter
296	 * after a successful call to cec_register_adapter().
297	 */
298	devm_remove_action(&pdev->dev, dw_hdmi_cec_del, cec);
299
300	cec_register_cec_notifier(cec->adap, cec->notify);
301
302	return 0;
303}
304
305static int dw_hdmi_cec_remove(struct platform_device *pdev)
306{
307	struct dw_hdmi_cec *cec = platform_get_drvdata(pdev);
308
309	cec_unregister_adapter(cec->adap);
310	cec_notifier_put(cec->notify);
311
312	return 0;
313}
314
315static struct platform_driver dw_hdmi_cec_driver = {
316	.probe	= dw_hdmi_cec_probe,
317	.remove	= dw_hdmi_cec_remove,
318	.driver = {
319		.name = "dw-hdmi-cec",
320	},
321};
322module_platform_driver(dw_hdmi_cec_driver);
323
324MODULE_AUTHOR("Russell King <rmk+kernel@armlinux.org.uk>");
325MODULE_DESCRIPTION("Synopsys Designware HDMI CEC driver for i.MX");
326MODULE_LICENSE("GPL");
327MODULE_ALIAS(PLATFORM_MODULE_PREFIX "dw-hdmi-cec");