1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * STIH4xx CEC driver
4  * Copyright (C) STMicroelectronics SA 2016
5  *
6  */
7 #include <linux/clk.h>
8 #include <linux/interrupt.h>
9 #include <linux/kernel.h>
10 #include <linux/mfd/syscon.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/of_platform.h>
14 #include <linux/platform_device.h>
15 
16 #include <media/cec.h>
17 #include <media/cec-notifier.h>
18 
19 #define CEC_NAME	"stih-cec"
20 
21 /* CEC registers  */
22 #define CEC_CLK_DIV           0x0
23 #define CEC_CTRL              0x4
24 #define CEC_IRQ_CTRL          0x8
25 #define CEC_STATUS            0xC
26 #define CEC_EXT_STATUS        0x10
27 #define CEC_TX_CTRL           0x14
28 #define CEC_FREE_TIME_THRESH  0x18
29 #define CEC_BIT_TOUT_THRESH   0x1C
30 #define CEC_BIT_PULSE_THRESH  0x20
31 #define CEC_DATA              0x24
32 #define CEC_TX_ARRAY_CTRL     0x28
33 #define CEC_CTRL2             0x2C
34 #define CEC_TX_ERROR_STS      0x30
35 #define CEC_ADDR_TABLE        0x34
36 #define CEC_DATA_ARRAY_CTRL   0x38
37 #define CEC_DATA_ARRAY_STATUS 0x3C
38 #define CEC_TX_DATA_BASE      0x40
39 #define CEC_TX_DATA_TOP       0x50
40 #define CEC_TX_DATA_SIZE      0x1
41 #define CEC_RX_DATA_BASE      0x54
42 #define CEC_RX_DATA_TOP       0x64
43 #define CEC_RX_DATA_SIZE      0x1
44 
45 /* CEC_CTRL2 */
46 #define CEC_LINE_INACTIVE_EN   BIT(0)
47 #define CEC_AUTO_BUS_ERR_EN    BIT(1)
48 #define CEC_STOP_ON_ARB_ERR_EN BIT(2)
49 #define CEC_TX_REQ_WAIT_EN     BIT(3)
50 
51 /* CEC_DATA_ARRAY_CTRL */
52 #define CEC_TX_ARRAY_EN          BIT(0)
53 #define CEC_RX_ARRAY_EN          BIT(1)
54 #define CEC_TX_ARRAY_RESET       BIT(2)
55 #define CEC_RX_ARRAY_RESET       BIT(3)
56 #define CEC_TX_N_OF_BYTES_IRQ_EN BIT(4)
57 #define CEC_TX_STOP_ON_NACK      BIT(7)
58 
59 /* CEC_TX_ARRAY_CTRL */
60 #define CEC_TX_N_OF_BYTES  0x1F
61 #define CEC_TX_START       BIT(5)
62 #define CEC_TX_AUTO_SOM_EN BIT(6)
63 #define CEC_TX_AUTO_EOM_EN BIT(7)
64 
65 /* CEC_IRQ_CTRL */
66 #define CEC_TX_DONE_IRQ_EN   BIT(0)
67 #define CEC_ERROR_IRQ_EN     BIT(2)
68 #define CEC_RX_DONE_IRQ_EN   BIT(3)
69 #define CEC_RX_SOM_IRQ_EN    BIT(4)
70 #define CEC_RX_EOM_IRQ_EN    BIT(5)
71 #define CEC_FREE_TIME_IRQ_EN BIT(6)
72 #define CEC_PIN_STS_IRQ_EN   BIT(7)
73 
74 /* CEC_CTRL */
75 #define CEC_IN_FILTER_EN    BIT(0)
76 #define CEC_PWR_SAVE_EN     BIT(1)
77 #define CEC_EN              BIT(4)
78 #define CEC_ACK_CTRL        BIT(5)
79 #define CEC_RX_RESET_EN     BIT(6)
80 #define CEC_IGNORE_RX_ERROR BIT(7)
81 
82 /* CEC_STATUS */
83 #define CEC_TX_DONE_STS       BIT(0)
84 #define CEC_TX_ACK_GET_STS    BIT(1)
85 #define CEC_ERROR_STS         BIT(2)
86 #define CEC_RX_DONE_STS       BIT(3)
87 #define CEC_RX_SOM_STS        BIT(4)
88 #define CEC_RX_EOM_STS        BIT(5)
89 #define CEC_FREE_TIME_IRQ_STS BIT(6)
90 #define CEC_PIN_STS           BIT(7)
91 #define CEC_SBIT_TOUT_STS     BIT(8)
92 #define CEC_DBIT_TOUT_STS     BIT(9)
93 #define CEC_LPULSE_ERROR_STS  BIT(10)
94 #define CEC_HPULSE_ERROR_STS  BIT(11)
95 #define CEC_TX_ERROR          BIT(12)
96 #define CEC_TX_ARB_ERROR      BIT(13)
97 #define CEC_RX_ERROR_MIN      BIT(14)
98 #define CEC_RX_ERROR_MAX      BIT(15)
99 
100 /* Signal free time in bit periods (2.4ms) */
101 #define CEC_PRESENT_INIT_SFT 7
102 #define CEC_NEW_INIT_SFT     5
103 #define CEC_RETRANSMIT_SFT   3
104 
105 /* Constants for CEC_BIT_TOUT_THRESH register */
106 #define CEC_SBIT_TOUT_47MS BIT(1)
107 #define CEC_SBIT_TOUT_48MS (BIT(0) | BIT(1))
108 #define CEC_SBIT_TOUT_50MS BIT(2)
109 #define CEC_DBIT_TOUT_27MS BIT(0)
110 #define CEC_DBIT_TOUT_28MS BIT(1)
111 #define CEC_DBIT_TOUT_29MS (BIT(0) | BIT(1))
112 
113 /* Constants for CEC_BIT_PULSE_THRESH register */
114 #define CEC_BIT_LPULSE_03MS BIT(1)
115 #define CEC_BIT_HPULSE_03MS BIT(3)
116 
117 /* Constants for CEC_DATA_ARRAY_STATUS register */
118 #define CEC_RX_N_OF_BYTES                     0x1F
119 #define CEC_TX_N_OF_BYTES_SENT                BIT(5)
120 #define CEC_RX_OVERRUN                        BIT(6)
121 
122 struct stih_cec {
123 	struct cec_adapter	*adap;
124 	struct device		*dev;
125 	struct clk		*clk;
126 	void __iomem		*regs;
127 	int			irq;
128 	u32			irq_status;
129 	struct cec_notifier	*notifier;
130 };
131 
132 static int stih_cec_adap_enable(struct cec_adapter *adap, bool enable)
133 {
134 	struct stih_cec *cec = cec_get_drvdata(adap);
135 
136 	if (enable) {
137 		/* The doc says (input TCLK_PERIOD * CEC_CLK_DIV) = 0.1ms */
138 		unsigned long clk_freq = clk_get_rate(cec->clk);
139 		u32 cec_clk_div = clk_freq / 10000;
140 
141 		writel(cec_clk_div, cec->regs + CEC_CLK_DIV);
142 
143 		/* Configuration of the durations activating a timeout */
144 		writel(CEC_SBIT_TOUT_47MS | (CEC_DBIT_TOUT_28MS << 4),
145 		       cec->regs + CEC_BIT_TOUT_THRESH);
146 
147 		/* Configuration of the smallest allowed duration for pulses */
148 		writel(CEC_BIT_LPULSE_03MS | CEC_BIT_HPULSE_03MS,
149 		       cec->regs + CEC_BIT_PULSE_THRESH);
150 
151 		/* Minimum received bit period threshold */
152 		writel(BIT(5) | BIT(7), cec->regs + CEC_TX_CTRL);
153 
154 		/* Configuration of transceiver data arrays */
155 		writel(CEC_TX_ARRAY_EN | CEC_RX_ARRAY_EN | CEC_TX_STOP_ON_NACK,
156 		       cec->regs + CEC_DATA_ARRAY_CTRL);
157 
158 		/* Configuration of the control bits for CEC Transceiver */
159 		writel(CEC_IN_FILTER_EN | CEC_EN | CEC_RX_RESET_EN,
160 		       cec->regs + CEC_CTRL);
161 
162 		/* Clear logical addresses */
163 		writel(0, cec->regs + CEC_ADDR_TABLE);
164 
165 		/* Clear the status register */
166 		writel(0x0, cec->regs + CEC_STATUS);
167 
168 		/* Enable the interrupts */
169 		writel(CEC_TX_DONE_IRQ_EN | CEC_RX_DONE_IRQ_EN |
170 		       CEC_RX_SOM_IRQ_EN | CEC_RX_EOM_IRQ_EN |
171 		       CEC_ERROR_IRQ_EN,
172 		       cec->regs + CEC_IRQ_CTRL);
173 
174 	} else {
175 		/* Clear logical addresses */
176 		writel(0, cec->regs + CEC_ADDR_TABLE);
177 
178 		/* Clear the status register */
179 		writel(0x0, cec->regs + CEC_STATUS);
180 
181 		/* Disable the interrupts */
182 		writel(0, cec->regs + CEC_IRQ_CTRL);
183 	}
184 
185 	return 0;
186 }
187 
188 static int stih_cec_adap_log_addr(struct cec_adapter *adap, u8 logical_addr)
189 {
190 	struct stih_cec *cec = cec_get_drvdata(adap);
191 	u32 reg = readl(cec->regs + CEC_ADDR_TABLE);
192 
193 	reg |= 1 << logical_addr;
194 
195 	if (logical_addr == CEC_LOG_ADDR_INVALID)
196 		reg = 0;
197 
198 	writel(reg, cec->regs + CEC_ADDR_TABLE);
199 
200 	return 0;
201 }
202 
203 static int stih_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
204 				  u32 signal_free_time, struct cec_msg *msg)
205 {
206 	struct stih_cec *cec = cec_get_drvdata(adap);
207 	int i;
208 
209 	/* Copy message into registers */
210 	for (i = 0; i < msg->len; i++)
211 		writeb(msg->msg[i], cec->regs + CEC_TX_DATA_BASE + i);
212 
213 	/*
214 	 * Start transmission, configure hardware to add start and stop bits
215 	 * Signal free time is handled by the hardware
216 	 */
217 	writel(CEC_TX_AUTO_SOM_EN | CEC_TX_AUTO_EOM_EN | CEC_TX_START |
218 	       msg->len, cec->regs + CEC_TX_ARRAY_CTRL);
219 
220 	return 0;
221 }
222 
223 static void stih_tx_done(struct stih_cec *cec, u32 status)
224 {
225 	if (status & CEC_TX_ERROR) {
226 		cec_transmit_attempt_done(cec->adap, CEC_TX_STATUS_ERROR);
227 		return;
228 	}
229 
230 	if (status & CEC_TX_ARB_ERROR) {
231 		cec_transmit_attempt_done(cec->adap, CEC_TX_STATUS_ARB_LOST);
232 		return;
233 	}
234 
235 	if (!(status & CEC_TX_ACK_GET_STS)) {
236 		cec_transmit_attempt_done(cec->adap, CEC_TX_STATUS_NACK);
237 		return;
238 	}
239 
240 	cec_transmit_attempt_done(cec->adap, CEC_TX_STATUS_OK);
241 }
242 
243 static void stih_rx_done(struct stih_cec *cec, u32 status)
244 {
245 	struct cec_msg msg = {};
246 	u8 i;
247 
248 	if (status & CEC_RX_ERROR_MIN)
249 		return;
250 
251 	if (status & CEC_RX_ERROR_MAX)
252 		return;
253 
254 	msg.len = readl(cec->regs + CEC_DATA_ARRAY_STATUS) & 0x1f;
255 
256 	if (!msg.len)
257 		return;
258 
259 	if (msg.len > CEC_MAX_MSG_SIZE)
260 		msg.len = CEC_MAX_MSG_SIZE;
261 
262 	for (i = 0; i < msg.len; i++)
263 		msg.msg[i] = readl(cec->regs + CEC_RX_DATA_BASE + i);
264 
265 	cec_received_msg(cec->adap, &msg);
266 }
267 
268 static irqreturn_t stih_cec_irq_handler_thread(int irq, void *priv)
269 {
270 	struct stih_cec *cec = priv;
271 
272 	if (cec->irq_status & CEC_TX_DONE_STS)
273 		stih_tx_done(cec, cec->irq_status);
274 
275 	if (cec->irq_status & CEC_RX_DONE_STS)
276 		stih_rx_done(cec, cec->irq_status);
277 
278 	cec->irq_status = 0;
279 
280 	return IRQ_HANDLED;
281 }
282 
283 static irqreturn_t stih_cec_irq_handler(int irq, void *priv)
284 {
285 	struct stih_cec *cec = priv;
286 
287 	cec->irq_status = readl(cec->regs + CEC_STATUS);
288 	writel(cec->irq_status, cec->regs + CEC_STATUS);
289 
290 	return IRQ_WAKE_THREAD;
291 }
292 
293 static const struct cec_adap_ops sti_cec_adap_ops = {
294 	.adap_enable = stih_cec_adap_enable,
295 	.adap_log_addr = stih_cec_adap_log_addr,
296 	.adap_transmit = stih_cec_adap_transmit,
297 };
298 
299 static int stih_cec_probe(struct platform_device *pdev)
300 {
301 	struct device *dev = &pdev->dev;
302 	struct stih_cec *cec;
303 	struct device *hdmi_dev;
304 	int ret;
305 
306 	hdmi_dev = cec_notifier_parse_hdmi_phandle(dev);
307 
308 	if (IS_ERR(hdmi_dev))
309 		return PTR_ERR(hdmi_dev);
310 
311 	cec = devm_kzalloc(dev, sizeof(*cec), GFP_KERNEL);
312 	if (!cec)
313 		return -ENOMEM;
314 
315 	cec->dev = dev;
316 
317 	cec->regs = devm_platform_ioremap_resource(pdev, 0);
318 	if (IS_ERR(cec->regs))
319 		return PTR_ERR(cec->regs);
320 
321 	cec->irq = platform_get_irq(pdev, 0);
322 	if (cec->irq < 0)
323 		return cec->irq;
324 
325 	ret = devm_request_threaded_irq(dev, cec->irq, stih_cec_irq_handler,
326 					stih_cec_irq_handler_thread, 0,
327 					pdev->name, cec);
328 	if (ret)
329 		return ret;
330 
331 	cec->clk = devm_clk_get(dev, "cec-clk");
332 	if (IS_ERR(cec->clk)) {
333 		dev_err(dev, "Cannot get cec clock\n");
334 		return PTR_ERR(cec->clk);
335 	}
336 
337 	cec->adap = cec_allocate_adapter(&sti_cec_adap_ops, cec, CEC_NAME,
338 					 CEC_CAP_DEFAULTS |
339 					 CEC_CAP_CONNECTOR_INFO,
340 					 CEC_MAX_LOG_ADDRS);
341 	ret = PTR_ERR_OR_ZERO(cec->adap);
342 	if (ret)
343 		return ret;
344 
345 	cec->notifier = cec_notifier_cec_adap_register(hdmi_dev, NULL,
346 						       cec->adap);
347 	if (!cec->notifier) {
348 		ret = -ENOMEM;
349 		goto err_delete_adapter;
350 	}
351 
352 	ret = cec_register_adapter(cec->adap, &pdev->dev);
353 	if (ret)
354 		goto err_notifier;
355 
356 	platform_set_drvdata(pdev, cec);
357 	return 0;
358 
359 err_notifier:
360 	cec_notifier_cec_adap_unregister(cec->notifier, cec->adap);
361 
362 err_delete_adapter:
363 	cec_delete_adapter(cec->adap);
364 	return ret;
365 }
366 
367 static void stih_cec_remove(struct platform_device *pdev)
368 {
369 	struct stih_cec *cec = platform_get_drvdata(pdev);
370 
371 	cec_notifier_cec_adap_unregister(cec->notifier, cec->adap);
372 	cec_unregister_adapter(cec->adap);
373 }
374 
375 static const struct of_device_id stih_cec_match[] = {
376 	{
377 		.compatible	= "st,stih-cec",
378 	},
379 	{},
380 };
381 MODULE_DEVICE_TABLE(of, stih_cec_match);
382 
383 static struct platform_driver stih_cec_pdrv = {
384 	.probe	= stih_cec_probe,
385 	.remove_new = stih_cec_remove,
386 	.driver = {
387 		.name		= CEC_NAME,
388 		.of_match_table	= stih_cec_match,
389 	},
390 };
391 
392 module_platform_driver(stih_cec_pdrv);
393 
394 MODULE_AUTHOR("Benjamin Gaignard <benjamin.gaignard@linaro.org>");
395 MODULE_LICENSE("GPL");
396 MODULE_DESCRIPTION("STIH4xx CEC driver");
397