xref: /linux/drivers/media/cec/platform/stm32/stm32-cec.c (revision a4eb44a6435d6d8f9e642407a4a06f65eb90ca04) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * STM32 CEC driver
4  * Copyright (C) STMicroelectronics SA 2017
5  *
6  */
7 
8 #include <linux/clk.h>
9 #include <linux/interrupt.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/of_device.h>
14 #include <linux/platform_device.h>
15 #include <linux/regmap.h>
16 
17 #include <media/cec.h>
18 
19 #define CEC_NAME	"stm32-cec"
20 
21 /* CEC registers  */
22 #define CEC_CR		0x0000 /* Control Register */
23 #define CEC_CFGR	0x0004 /* ConFiGuration Register */
24 #define CEC_TXDR	0x0008 /* Rx data Register */
25 #define CEC_RXDR	0x000C /* Rx data Register */
26 #define CEC_ISR		0x0010 /* Interrupt and status Register */
27 #define CEC_IER		0x0014 /* Interrupt enable Register */
28 
29 #define TXEOM		BIT(2)
30 #define TXSOM		BIT(1)
31 #define CECEN		BIT(0)
32 
33 #define LSTN		BIT(31)
34 #define OAR		GENMASK(30, 16)
35 #define SFTOP		BIT(8)
36 #define BRDNOGEN	BIT(7)
37 #define LBPEGEN		BIT(6)
38 #define BREGEN		BIT(5)
39 #define BRESTP		BIT(4)
40 #define RXTOL		BIT(3)
41 #define SFT		GENMASK(2, 0)
42 #define FULL_CFG	(LSTN | SFTOP | BRDNOGEN | LBPEGEN | BREGEN | BRESTP \
43 			 | RXTOL)
44 
45 #define TXACKE		BIT(12)
46 #define TXERR		BIT(11)
47 #define TXUDR		BIT(10)
48 #define TXEND		BIT(9)
49 #define TXBR		BIT(8)
50 #define ARBLST		BIT(7)
51 #define RXACKE		BIT(6)
52 #define RXOVR		BIT(2)
53 #define RXEND		BIT(1)
54 #define RXBR		BIT(0)
55 
56 #define ALL_TX_IT	(TXEND | TXBR | TXACKE | TXERR | TXUDR | ARBLST)
57 #define ALL_RX_IT	(RXEND | RXBR | RXACKE | RXOVR)
58 
59 /*
60  * 400 ms is the time it takes for one 16 byte message to be
61  * transferred and 5 is the maximum number of retries. Add
62  * another 100 ms as a margin.
63  */
64 #define CEC_XFER_TIMEOUT_MS (5 * 400 + 100)
65 
66 struct stm32_cec {
67 	struct cec_adapter	*adap;
68 	struct device		*dev;
69 	struct clk		*clk_cec;
70 	struct clk		*clk_hdmi_cec;
71 	struct reset_control	*rstc;
72 	struct regmap		*regmap;
73 	int			irq;
74 	u32			irq_status;
75 	struct cec_msg		rx_msg;
76 	struct cec_msg		tx_msg;
77 	int			tx_cnt;
78 };
79 
80 static void cec_hw_init(struct stm32_cec *cec)
81 {
82 	regmap_update_bits(cec->regmap, CEC_CR, TXEOM | TXSOM | CECEN, 0);
83 
84 	regmap_update_bits(cec->regmap, CEC_IER, ALL_TX_IT | ALL_RX_IT,
85 			   ALL_TX_IT | ALL_RX_IT);
86 
87 	regmap_update_bits(cec->regmap, CEC_CFGR, FULL_CFG, FULL_CFG);
88 }
89 
90 static void stm32_tx_done(struct stm32_cec *cec, u32 status)
91 {
92 	if (status & (TXERR | TXUDR)) {
93 		cec_transmit_done(cec->adap, CEC_TX_STATUS_ERROR,
94 				  0, 0, 0, 1);
95 		return;
96 	}
97 
98 	if (status & ARBLST) {
99 		cec_transmit_done(cec->adap, CEC_TX_STATUS_ARB_LOST,
100 				  1, 0, 0, 0);
101 		return;
102 	}
103 
104 	if (status & TXACKE) {
105 		cec_transmit_done(cec->adap, CEC_TX_STATUS_NACK,
106 				  0, 1, 0, 0);
107 		return;
108 	}
109 
110 	if (cec->irq_status & TXBR) {
111 		/* send next byte */
112 		if (cec->tx_cnt < cec->tx_msg.len)
113 			regmap_write(cec->regmap, CEC_TXDR,
114 				     cec->tx_msg.msg[cec->tx_cnt++]);
115 
116 		/* TXEOM is set to command transmission of the last byte */
117 		if (cec->tx_cnt == cec->tx_msg.len)
118 			regmap_update_bits(cec->regmap, CEC_CR, TXEOM, TXEOM);
119 	}
120 
121 	if (cec->irq_status & TXEND)
122 		cec_transmit_done(cec->adap, CEC_TX_STATUS_OK, 0, 0, 0, 0);
123 }
124 
125 static void stm32_rx_done(struct stm32_cec *cec, u32 status)
126 {
127 	if (cec->irq_status & (RXACKE | RXOVR)) {
128 		cec->rx_msg.len = 0;
129 		return;
130 	}
131 
132 	if (cec->irq_status & RXBR) {
133 		u32 val;
134 
135 		regmap_read(cec->regmap, CEC_RXDR, &val);
136 		cec->rx_msg.msg[cec->rx_msg.len++] = val & 0xFF;
137 	}
138 
139 	if (cec->irq_status & RXEND) {
140 		cec_received_msg(cec->adap, &cec->rx_msg);
141 		cec->rx_msg.len = 0;
142 	}
143 }
144 
145 static irqreturn_t stm32_cec_irq_thread(int irq, void *arg)
146 {
147 	struct stm32_cec *cec = arg;
148 
149 	if (cec->irq_status & ALL_TX_IT)
150 		stm32_tx_done(cec, cec->irq_status);
151 
152 	if (cec->irq_status & ALL_RX_IT)
153 		stm32_rx_done(cec, cec->irq_status);
154 
155 	cec->irq_status = 0;
156 
157 	return IRQ_HANDLED;
158 }
159 
160 static irqreturn_t stm32_cec_irq_handler(int irq, void *arg)
161 {
162 	struct stm32_cec *cec = arg;
163 
164 	regmap_read(cec->regmap, CEC_ISR, &cec->irq_status);
165 
166 	regmap_update_bits(cec->regmap, CEC_ISR,
167 			   ALL_TX_IT | ALL_RX_IT,
168 			   ALL_TX_IT | ALL_RX_IT);
169 
170 	return IRQ_WAKE_THREAD;
171 }
172 
173 static int stm32_cec_adap_enable(struct cec_adapter *adap, bool enable)
174 {
175 	struct stm32_cec *cec = adap->priv;
176 	int ret = 0;
177 
178 	if (enable) {
179 		ret = clk_enable(cec->clk_cec);
180 		if (ret)
181 			dev_err(cec->dev, "fail to enable cec clock\n");
182 
183 		clk_enable(cec->clk_hdmi_cec);
184 		regmap_update_bits(cec->regmap, CEC_CR, CECEN, CECEN);
185 	} else {
186 		clk_disable(cec->clk_cec);
187 		clk_disable(cec->clk_hdmi_cec);
188 		regmap_update_bits(cec->regmap, CEC_CR, CECEN, 0);
189 	}
190 
191 	return ret;
192 }
193 
194 static int stm32_cec_adap_log_addr(struct cec_adapter *adap, u8 logical_addr)
195 {
196 	struct stm32_cec *cec = adap->priv;
197 	u32 oar = (1 << logical_addr) << 16;
198 	u32 val;
199 
200 	/* Poll every 100µs the register CEC_CR to wait end of transmission */
201 	regmap_read_poll_timeout(cec->regmap, CEC_CR, val, !(val & TXSOM),
202 				 100, CEC_XFER_TIMEOUT_MS * 1000);
203 	regmap_update_bits(cec->regmap, CEC_CR, CECEN, 0);
204 
205 	if (logical_addr == CEC_LOG_ADDR_INVALID)
206 		regmap_update_bits(cec->regmap, CEC_CFGR, OAR, 0);
207 	else
208 		regmap_update_bits(cec->regmap, CEC_CFGR, oar, oar);
209 
210 	regmap_update_bits(cec->regmap, CEC_CR, CECEN, CECEN);
211 
212 	return 0;
213 }
214 
215 static int stm32_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
216 				   u32 signal_free_time, struct cec_msg *msg)
217 {
218 	struct stm32_cec *cec = adap->priv;
219 
220 	/* Copy message */
221 	cec->tx_msg = *msg;
222 	cec->tx_cnt = 0;
223 
224 	/*
225 	 * If the CEC message consists of only one byte,
226 	 * TXEOM must be set before of TXSOM.
227 	 */
228 	if (cec->tx_msg.len == 1)
229 		regmap_update_bits(cec->regmap, CEC_CR, TXEOM, TXEOM);
230 
231 	/* TXSOM is set to command transmission of the first byte */
232 	regmap_update_bits(cec->regmap, CEC_CR, TXSOM, TXSOM);
233 
234 	/* Write the header (first byte of message) */
235 	regmap_write(cec->regmap, CEC_TXDR, cec->tx_msg.msg[0]);
236 	cec->tx_cnt++;
237 
238 	return 0;
239 }
240 
241 static const struct cec_adap_ops stm32_cec_adap_ops = {
242 	.adap_enable = stm32_cec_adap_enable,
243 	.adap_log_addr = stm32_cec_adap_log_addr,
244 	.adap_transmit = stm32_cec_adap_transmit,
245 };
246 
247 static const struct regmap_config stm32_cec_regmap_cfg = {
248 	.reg_bits = 32,
249 	.val_bits = 32,
250 	.reg_stride = sizeof(u32),
251 	.max_register = 0x14,
252 	.fast_io = true,
253 };
254 
255 static int stm32_cec_probe(struct platform_device *pdev)
256 {
257 	u32 caps = CEC_CAP_DEFAULTS | CEC_CAP_PHYS_ADDR | CEC_MODE_MONITOR_ALL;
258 	struct stm32_cec *cec;
259 	void __iomem *mmio;
260 	int ret;
261 
262 	cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
263 	if (!cec)
264 		return -ENOMEM;
265 
266 	cec->dev = &pdev->dev;
267 
268 	mmio = devm_platform_ioremap_resource(pdev, 0);
269 	if (IS_ERR(mmio))
270 		return PTR_ERR(mmio);
271 
272 	cec->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "cec", mmio,
273 						&stm32_cec_regmap_cfg);
274 
275 	if (IS_ERR(cec->regmap))
276 		return PTR_ERR(cec->regmap);
277 
278 	cec->irq = platform_get_irq(pdev, 0);
279 	if (cec->irq < 0)
280 		return cec->irq;
281 
282 	ret = devm_request_threaded_irq(&pdev->dev, cec->irq,
283 					stm32_cec_irq_handler,
284 					stm32_cec_irq_thread,
285 					0,
286 					pdev->name, cec);
287 	if (ret)
288 		return ret;
289 
290 	cec->clk_cec = devm_clk_get(&pdev->dev, "cec");
291 	if (IS_ERR(cec->clk_cec)) {
292 		if (PTR_ERR(cec->clk_cec) != -EPROBE_DEFER)
293 			dev_err(&pdev->dev, "Cannot get cec clock\n");
294 
295 		return PTR_ERR(cec->clk_cec);
296 	}
297 
298 	ret = clk_prepare(cec->clk_cec);
299 	if (ret) {
300 		dev_err(&pdev->dev, "Unable to prepare cec clock\n");
301 		return ret;
302 	}
303 
304 	cec->clk_hdmi_cec = devm_clk_get(&pdev->dev, "hdmi-cec");
305 	if (IS_ERR(cec->clk_hdmi_cec) &&
306 	    PTR_ERR(cec->clk_hdmi_cec) == -EPROBE_DEFER) {
307 		ret = -EPROBE_DEFER;
308 		goto err_unprepare_cec_clk;
309 	}
310 
311 	if (!IS_ERR(cec->clk_hdmi_cec)) {
312 		ret = clk_prepare(cec->clk_hdmi_cec);
313 		if (ret) {
314 			dev_err(&pdev->dev, "Can't prepare hdmi-cec clock\n");
315 			goto err_unprepare_cec_clk;
316 		}
317 	}
318 
319 	/*
320 	 * CEC_CAP_PHYS_ADDR caps should be removed when a cec notifier is
321 	 * available for example when a drm driver can provide edid
322 	 */
323 	cec->adap = cec_allocate_adapter(&stm32_cec_adap_ops, cec,
324 			CEC_NAME, caps,	CEC_MAX_LOG_ADDRS);
325 	ret = PTR_ERR_OR_ZERO(cec->adap);
326 	if (ret)
327 		goto err_unprepare_hdmi_cec_clk;
328 
329 	ret = cec_register_adapter(cec->adap, &pdev->dev);
330 	if (ret)
331 		goto err_delete_adapter;
332 
333 	cec_hw_init(cec);
334 
335 	platform_set_drvdata(pdev, cec);
336 
337 	return 0;
338 
339 err_delete_adapter:
340 	cec_delete_adapter(cec->adap);
341 
342 err_unprepare_hdmi_cec_clk:
343 	clk_unprepare(cec->clk_hdmi_cec);
344 
345 err_unprepare_cec_clk:
346 	clk_unprepare(cec->clk_cec);
347 	return ret;
348 }
349 
350 static int stm32_cec_remove(struct platform_device *pdev)
351 {
352 	struct stm32_cec *cec = platform_get_drvdata(pdev);
353 
354 	clk_unprepare(cec->clk_cec);
355 	clk_unprepare(cec->clk_hdmi_cec);
356 
357 	cec_unregister_adapter(cec->adap);
358 
359 	return 0;
360 }
361 
362 static const struct of_device_id stm32_cec_of_match[] = {
363 	{ .compatible = "st,stm32-cec" },
364 	{ /* end node */ }
365 };
366 MODULE_DEVICE_TABLE(of, stm32_cec_of_match);
367 
368 static struct platform_driver stm32_cec_driver = {
369 	.probe  = stm32_cec_probe,
370 	.remove = stm32_cec_remove,
371 	.driver = {
372 		.name		= CEC_NAME,
373 		.of_match_table = stm32_cec_of_match,
374 	},
375 };
376 
377 module_platform_driver(stm32_cec_driver);
378 
379 MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@st.com>");
380 MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>");
381 MODULE_DESCRIPTION("STMicroelectronics STM32 Consumer Electronics Control");
382 MODULE_LICENSE("GPL v2");
383