1 /*
2  * Platform CAN bus driver for Bosch C_CAN controller
3  *
4  * Copyright (C) 2010 ST Microelectronics
5  * Bhupesh Sharma <bhupesh.sharma@st.com>
6  *
7  * Borrowed heavily from the C_CAN driver originally written by:
8  * Copyright (C) 2007
9  * - Sascha Hauer, Marc Kleine-Budde, Pengutronix <s.hauer@pengutronix.de>
10  * - Simon Kallweit, intefo AG <simon.kallweit@intefo.ch>
11  *
12  * Bosch C_CAN controller is compliant to CAN protocol version 2.0 part A and B.
13  * Bosch C_CAN user manual can be obtained from:
14  * http://www.semiconductors.bosch.de/media/en/pdf/ipmodules_1/c_can/
15  * users_manual_c_can.pdf
16  *
17  * This file is licensed under the terms of the GNU General Public
18  * License version 2. This program is licensed "as is" without any
19  * warranty of any kind, whether express or implied.
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/interrupt.h>
25 #include <linux/delay.h>
26 #include <linux/netdevice.h>
27 #include <linux/if_arp.h>
28 #include <linux/if_ether.h>
29 #include <linux/list.h>
30 #include <linux/io.h>
31 #include <linux/platform_device.h>
32 #include <linux/pm_runtime.h>
33 #include <linux/clk.h>
34 #include <linux/of.h>
35 #include <linux/of_device.h>
36 #include <linux/mfd/syscon.h>
37 #include <linux/regmap.h>
38 
39 #include <linux/can/dev.h>
40 
41 #include "c_can.h"
42 
43 #define DCAN_RAM_INIT_BIT BIT(3)
44 
45 static DEFINE_SPINLOCK(raminit_lock);
46 
47 /* 16-bit c_can registers can be arranged differently in the memory
48  * architecture of different implementations. For example: 16-bit
49  * registers can be aligned to a 16-bit boundary or 32-bit boundary etc.
50  * Handle the same by providing a common read/write interface.
51  */
52 static u16 c_can_plat_read_reg_aligned_to_16bit(const struct c_can_priv *priv,
53 						enum reg index)
54 {
55 	return readw(priv->base + priv->regs[index]);
56 }
57 
58 static void c_can_plat_write_reg_aligned_to_16bit(const struct c_can_priv *priv,
59 						  enum reg index, u16 val)
60 {
61 	writew(val, priv->base + priv->regs[index]);
62 }
63 
64 static u16 c_can_plat_read_reg_aligned_to_32bit(const struct c_can_priv *priv,
65 						enum reg index)
66 {
67 	return readw(priv->base + 2 * priv->regs[index]);
68 }
69 
70 static void c_can_plat_write_reg_aligned_to_32bit(const struct c_can_priv *priv,
71 						  enum reg index, u16 val)
72 {
73 	writew(val, priv->base + 2 * priv->regs[index]);
74 }
75 
76 static void c_can_hw_raminit_wait_syscon(const struct c_can_priv *priv,
77 					 u32 mask, u32 val)
78 {
79 	const struct c_can_raminit *raminit = &priv->raminit_sys;
80 	int timeout = 0;
81 	u32 ctrl = 0;
82 
83 	/* We look only at the bits of our instance. */
84 	val &= mask;
85 	do {
86 		udelay(1);
87 		timeout++;
88 
89 		regmap_read(raminit->syscon, raminit->reg, &ctrl);
90 		if (timeout == 1000) {
91 			dev_err(&priv->dev->dev, "%s: time out\n", __func__);
92 			break;
93 		}
94 	} while ((ctrl & mask) != val);
95 }
96 
97 static void c_can_hw_raminit_syscon(const struct c_can_priv *priv, bool enable)
98 {
99 	const struct c_can_raminit *raminit = &priv->raminit_sys;
100 	u32 ctrl = 0;
101 	u32 mask;
102 
103 	spin_lock(&raminit_lock);
104 
105 	mask = 1 << raminit->bits.start | 1 << raminit->bits.done;
106 	regmap_read(raminit->syscon, raminit->reg, &ctrl);
107 
108 	/* We clear the start bit first. The start bit is
109 	 * looking at the 0 -> transition, but is not self clearing;
110 	 * NOTE: DONE must be written with 1 to clear it.
111 	 * We can't clear the DONE bit here using regmap_update_bits()
112 	 * as it will bypass the write if initial condition is START:0 DONE:1
113 	 * e.g. on DRA7 which needs START pulse.
114 	 */
115 	ctrl &= ~mask;	/* START = 0, DONE = 0 */
116 	regmap_update_bits(raminit->syscon, raminit->reg, mask, ctrl);
117 
118 	/* check if START bit is 0. Ignore DONE bit for now
119 	 * as it can be either 0 or 1.
120 	 */
121 	c_can_hw_raminit_wait_syscon(priv, 1 << raminit->bits.start, ctrl);
122 
123 	if (enable) {
124 		/* Clear DONE bit & set START bit. */
125 		ctrl |= 1 << raminit->bits.start;
126 		/* DONE must be written with 1 to clear it */
127 		ctrl |= 1 << raminit->bits.done;
128 		regmap_update_bits(raminit->syscon, raminit->reg, mask, ctrl);
129 		/* prevent further clearing of DONE bit */
130 		ctrl &= ~(1 << raminit->bits.done);
131 		/* clear START bit if start pulse is needed */
132 		if (raminit->needs_pulse) {
133 			ctrl &= ~(1 << raminit->bits.start);
134 			regmap_update_bits(raminit->syscon, raminit->reg,
135 					   mask, ctrl);
136 		}
137 
138 		ctrl |= 1 << raminit->bits.done;
139 		c_can_hw_raminit_wait_syscon(priv, mask, ctrl);
140 	}
141 	spin_unlock(&raminit_lock);
142 }
143 
144 static u32 c_can_plat_read_reg32(const struct c_can_priv *priv, enum reg index)
145 {
146 	u32 val;
147 
148 	val = priv->read_reg(priv, index);
149 	val |= ((u32)priv->read_reg(priv, index + 1)) << 16;
150 
151 	return val;
152 }
153 
154 static void c_can_plat_write_reg32(const struct c_can_priv *priv,
155 				   enum reg index, u32 val)
156 {
157 	priv->write_reg(priv, index + 1, val >> 16);
158 	priv->write_reg(priv, index, val);
159 }
160 
161 static u32 d_can_plat_read_reg32(const struct c_can_priv *priv, enum reg index)
162 {
163 	return readl(priv->base + priv->regs[index]);
164 }
165 
166 static void d_can_plat_write_reg32(const struct c_can_priv *priv,
167 				   enum reg index, u32 val)
168 {
169 	writel(val, priv->base + priv->regs[index]);
170 }
171 
172 static void c_can_hw_raminit_wait(const struct c_can_priv *priv, u32 mask)
173 {
174 	while (priv->read_reg32(priv, C_CAN_FUNCTION_REG) & mask)
175 		udelay(1);
176 }
177 
178 static void c_can_hw_raminit(const struct c_can_priv *priv, bool enable)
179 {
180 	u32 ctrl;
181 
182 	ctrl = priv->read_reg32(priv, C_CAN_FUNCTION_REG);
183 	ctrl &= ~DCAN_RAM_INIT_BIT;
184 	priv->write_reg32(priv, C_CAN_FUNCTION_REG, ctrl);
185 	c_can_hw_raminit_wait(priv, ctrl);
186 
187 	if (enable) {
188 		ctrl |= DCAN_RAM_INIT_BIT;
189 		priv->write_reg32(priv, C_CAN_FUNCTION_REG, ctrl);
190 		c_can_hw_raminit_wait(priv, ctrl);
191 	}
192 }
193 
194 static const struct c_can_driver_data c_can_drvdata = {
195 	.id = BOSCH_C_CAN,
196 	.msg_obj_num = 32,
197 };
198 
199 static const struct c_can_driver_data d_can_drvdata = {
200 	.id = BOSCH_D_CAN,
201 	.msg_obj_num = 32,
202 };
203 
204 static const struct raminit_bits dra7_raminit_bits[] = {
205 	[0] = { .start = 3, .done = 1, },
206 	[1] = { .start = 5, .done = 2, },
207 };
208 
209 static const struct c_can_driver_data dra7_dcan_drvdata = {
210 	.id = BOSCH_D_CAN,
211 	.msg_obj_num = 64,
212 	.raminit_num = ARRAY_SIZE(dra7_raminit_bits),
213 	.raminit_bits = dra7_raminit_bits,
214 	.raminit_pulse = true,
215 };
216 
217 static const struct raminit_bits am3352_raminit_bits[] = {
218 	[0] = { .start = 0, .done = 8, },
219 	[1] = { .start = 1, .done = 9, },
220 };
221 
222 static const struct c_can_driver_data am3352_dcan_drvdata = {
223 	.id = BOSCH_D_CAN,
224 	.msg_obj_num = 64,
225 	.raminit_num = ARRAY_SIZE(am3352_raminit_bits),
226 	.raminit_bits = am3352_raminit_bits,
227 };
228 
229 static const struct platform_device_id c_can_id_table[] = {
230 	{
231 		.name = KBUILD_MODNAME,
232 		.driver_data = (kernel_ulong_t)&c_can_drvdata,
233 	},
234 	{
235 		.name = "c_can",
236 		.driver_data = (kernel_ulong_t)&c_can_drvdata,
237 	},
238 	{
239 		.name = "d_can",
240 		.driver_data = (kernel_ulong_t)&d_can_drvdata,
241 	},
242 	{ /* sentinel */ },
243 };
244 MODULE_DEVICE_TABLE(platform, c_can_id_table);
245 
246 static const struct of_device_id c_can_of_table[] = {
247 	{ .compatible = "bosch,c_can", .data = &c_can_drvdata },
248 	{ .compatible = "bosch,d_can", .data = &d_can_drvdata },
249 	{ .compatible = "ti,dra7-d_can", .data = &dra7_dcan_drvdata },
250 	{ .compatible = "ti,am3352-d_can", .data = &am3352_dcan_drvdata },
251 	{ .compatible = "ti,am4372-d_can", .data = &am3352_dcan_drvdata },
252 	{ /* sentinel */ },
253 };
254 MODULE_DEVICE_TABLE(of, c_can_of_table);
255 
256 static int c_can_plat_probe(struct platform_device *pdev)
257 {
258 	int ret;
259 	void __iomem *addr;
260 	struct net_device *dev;
261 	struct c_can_priv *priv;
262 	const struct of_device_id *match;
263 	struct resource *mem;
264 	int irq;
265 	struct clk *clk;
266 	const struct c_can_driver_data *drvdata;
267 	struct device_node *np = pdev->dev.of_node;
268 
269 	match = of_match_device(c_can_of_table, &pdev->dev);
270 	if (match) {
271 		drvdata = match->data;
272 	} else if (pdev->id_entry->driver_data) {
273 		drvdata = (struct c_can_driver_data *)
274 			platform_get_device_id(pdev)->driver_data;
275 	} else {
276 		return -ENODEV;
277 	}
278 
279 	/* get the appropriate clk */
280 	clk = devm_clk_get(&pdev->dev, NULL);
281 	if (IS_ERR(clk)) {
282 		ret = PTR_ERR(clk);
283 		goto exit;
284 	}
285 
286 	/* get the platform data */
287 	irq = platform_get_irq(pdev, 0);
288 	if (irq <= 0) {
289 		ret = -ENODEV;
290 		goto exit;
291 	}
292 
293 	addr = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
294 	if (IS_ERR(addr)) {
295 		ret =  PTR_ERR(addr);
296 		goto exit;
297 	}
298 
299 	/* allocate the c_can device */
300 	dev = alloc_c_can_dev(drvdata->msg_obj_num);
301 	if (!dev) {
302 		ret = -ENOMEM;
303 		goto exit;
304 	}
305 
306 	priv = netdev_priv(dev);
307 	switch (drvdata->id) {
308 	case BOSCH_C_CAN:
309 		priv->regs = reg_map_c_can;
310 		switch (mem->flags & IORESOURCE_MEM_TYPE_MASK) {
311 		case IORESOURCE_MEM_32BIT:
312 			priv->read_reg = c_can_plat_read_reg_aligned_to_32bit;
313 			priv->write_reg = c_can_plat_write_reg_aligned_to_32bit;
314 			priv->read_reg32 = c_can_plat_read_reg32;
315 			priv->write_reg32 = c_can_plat_write_reg32;
316 			break;
317 		case IORESOURCE_MEM_16BIT:
318 		default:
319 			priv->read_reg = c_can_plat_read_reg_aligned_to_16bit;
320 			priv->write_reg = c_can_plat_write_reg_aligned_to_16bit;
321 			priv->read_reg32 = c_can_plat_read_reg32;
322 			priv->write_reg32 = c_can_plat_write_reg32;
323 			break;
324 		}
325 		break;
326 	case BOSCH_D_CAN:
327 		priv->regs = reg_map_d_can;
328 		priv->read_reg = c_can_plat_read_reg_aligned_to_16bit;
329 		priv->write_reg = c_can_plat_write_reg_aligned_to_16bit;
330 		priv->read_reg32 = d_can_plat_read_reg32;
331 		priv->write_reg32 = d_can_plat_write_reg32;
332 
333 		/* Check if we need custom RAMINIT via syscon. Mostly for TI
334 		 * platforms. Only supported with DT boot.
335 		 */
336 		if (np && of_property_read_bool(np, "syscon-raminit")) {
337 			u32 id;
338 			struct c_can_raminit *raminit = &priv->raminit_sys;
339 
340 			ret = -EINVAL;
341 			raminit->syscon = syscon_regmap_lookup_by_phandle(np,
342 									  "syscon-raminit");
343 			if (IS_ERR(raminit->syscon)) {
344 				/* can fail with -EPROBE_DEFER */
345 				ret = PTR_ERR(raminit->syscon);
346 				free_c_can_dev(dev);
347 				return ret;
348 			}
349 
350 			if (of_property_read_u32_index(np, "syscon-raminit", 1,
351 						       &raminit->reg)) {
352 				dev_err(&pdev->dev,
353 					"couldn't get the RAMINIT reg. offset!\n");
354 				goto exit_free_device;
355 			}
356 
357 			if (of_property_read_u32_index(np, "syscon-raminit", 2,
358 						       &id)) {
359 				dev_err(&pdev->dev,
360 					"couldn't get the CAN instance ID\n");
361 				goto exit_free_device;
362 			}
363 
364 			if (id >= drvdata->raminit_num) {
365 				dev_err(&pdev->dev,
366 					"Invalid CAN instance ID\n");
367 				goto exit_free_device;
368 			}
369 
370 			raminit->bits = drvdata->raminit_bits[id];
371 			raminit->needs_pulse = drvdata->raminit_pulse;
372 
373 			priv->raminit = c_can_hw_raminit_syscon;
374 		} else {
375 			priv->raminit = c_can_hw_raminit;
376 		}
377 		break;
378 	default:
379 		ret = -EINVAL;
380 		goto exit_free_device;
381 	}
382 
383 	dev->irq = irq;
384 	priv->base = addr;
385 	priv->device = &pdev->dev;
386 	priv->can.clock.freq = clk_get_rate(clk);
387 	priv->type = drvdata->id;
388 
389 	platform_set_drvdata(pdev, dev);
390 	SET_NETDEV_DEV(dev, &pdev->dev);
391 
392 	pm_runtime_enable(priv->device);
393 	ret = register_c_can_dev(dev);
394 	if (ret) {
395 		dev_err(&pdev->dev, "registering %s failed (err=%d)\n",
396 			KBUILD_MODNAME, ret);
397 		goto exit_free_device;
398 	}
399 
400 	dev_info(&pdev->dev, "%s device registered (regs=%p, irq=%d)\n",
401 		 KBUILD_MODNAME, priv->base, dev->irq);
402 	return 0;
403 
404 exit_free_device:
405 	pm_runtime_disable(priv->device);
406 	free_c_can_dev(dev);
407 exit:
408 	dev_err(&pdev->dev, "probe failed\n");
409 
410 	return ret;
411 }
412 
413 static void c_can_plat_remove(struct platform_device *pdev)
414 {
415 	struct net_device *dev = platform_get_drvdata(pdev);
416 	struct c_can_priv *priv = netdev_priv(dev);
417 
418 	unregister_c_can_dev(dev);
419 	pm_runtime_disable(priv->device);
420 	free_c_can_dev(dev);
421 }
422 
423 #ifdef CONFIG_PM
424 static int c_can_suspend(struct platform_device *pdev, pm_message_t state)
425 {
426 	int ret;
427 	struct net_device *ndev = platform_get_drvdata(pdev);
428 	struct c_can_priv *priv = netdev_priv(ndev);
429 
430 	if (priv->type != BOSCH_D_CAN) {
431 		dev_warn(&pdev->dev, "Not supported\n");
432 		return 0;
433 	}
434 
435 	if (netif_running(ndev)) {
436 		netif_stop_queue(ndev);
437 		netif_device_detach(ndev);
438 	}
439 
440 	ret = c_can_power_down(ndev);
441 	if (ret) {
442 		netdev_err(ndev, "failed to enter power down mode\n");
443 		return ret;
444 	}
445 
446 	priv->can.state = CAN_STATE_SLEEPING;
447 
448 	return 0;
449 }
450 
451 static int c_can_resume(struct platform_device *pdev)
452 {
453 	int ret;
454 	struct net_device *ndev = platform_get_drvdata(pdev);
455 	struct c_can_priv *priv = netdev_priv(ndev);
456 
457 	if (priv->type != BOSCH_D_CAN) {
458 		dev_warn(&pdev->dev, "Not supported\n");
459 		return 0;
460 	}
461 
462 	ret = c_can_power_up(ndev);
463 	if (ret) {
464 		netdev_err(ndev, "Still in power down mode\n");
465 		return ret;
466 	}
467 
468 	priv->can.state = CAN_STATE_ERROR_ACTIVE;
469 
470 	if (netif_running(ndev)) {
471 		netif_device_attach(ndev);
472 		netif_start_queue(ndev);
473 	}
474 
475 	return 0;
476 }
477 #else
478 #define c_can_suspend NULL
479 #define c_can_resume NULL
480 #endif
481 
482 static struct platform_driver c_can_plat_driver = {
483 	.driver = {
484 		.name = KBUILD_MODNAME,
485 		.of_match_table = c_can_of_table,
486 	},
487 	.probe = c_can_plat_probe,
488 	.remove_new = c_can_plat_remove,
489 	.suspend = c_can_suspend,
490 	.resume = c_can_resume,
491 	.id_table = c_can_id_table,
492 };
493 
494 module_platform_driver(c_can_plat_driver);
495 
496 MODULE_AUTHOR("Bhupesh Sharma <bhupesh.sharma@st.com>");
497 MODULE_LICENSE("GPL v2");
498 MODULE_DESCRIPTION("Platform CAN bus driver for Bosch C_CAN controller");
499