1/*
2 * Copyright Altera Corporation (C) 2013-2014. All rights reserved
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms and conditions of the GNU General Public License,
6 * version 2, as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program.  If not, see <http://www.gnu.org/licenses/>.
15 */
16
17#include <linux/device.h>
18#include <linux/interrupt.h>
19#include <linux/io.h>
20#include <linux/kernel.h>
21#include <linux/mailbox_controller.h>
22#include <linux/module.h>
23#include <linux/of.h>
24#include <linux/platform_device.h>
25
26#define DRIVER_NAME	"altera-mailbox"
27
28#define MAILBOX_CMD_REG			0x00
29#define MAILBOX_PTR_REG			0x04
30#define MAILBOX_STS_REG			0x08
31#define MAILBOX_INTMASK_REG		0x0C
32
33#define INT_PENDING_MSK			0x1
34#define INT_SPACE_MSK			0x2
35
36#define STS_PENDING_MSK			0x1
37#define STS_FULL_MSK			0x2
38#define STS_FULL_OFT			0x1
39
40#define MBOX_PENDING(status)	(((status) & STS_PENDING_MSK))
41#define MBOX_FULL(status)	(((status) & STS_FULL_MSK) >> STS_FULL_OFT)
42
43enum altera_mbox_msg {
44	MBOX_CMD = 0,
45	MBOX_PTR,
46};
47
48#define MBOX_POLLING_MS		5	/* polling interval 5ms */
49
50struct altera_mbox {
51	bool is_sender;		/* 1-sender, 0-receiver */
52	bool intr_mode;
53	int irq;
54	void __iomem *mbox_base;
55	struct device *dev;
56	struct mbox_controller controller;
57
58	/* If the controller supports only RX polling mode */
59	struct timer_list rxpoll_timer;
60};
61
62static struct altera_mbox *mbox_chan_to_altera_mbox(struct mbox_chan *chan)
63{
64	if (!chan || !chan->con_priv)
65		return NULL;
66
67	return (struct altera_mbox *)chan->con_priv;
68}
69
70static inline int altera_mbox_full(struct altera_mbox *mbox)
71{
72	u32 status;
73
74	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
75	return MBOX_FULL(status);
76}
77
78static inline int altera_mbox_pending(struct altera_mbox *mbox)
79{
80	u32 status;
81
82	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
83	return MBOX_PENDING(status);
84}
85
86static void altera_mbox_rx_intmask(struct altera_mbox *mbox, bool enable)
87{
88	u32 mask;
89
90	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
91	if (enable)
92		mask |= INT_PENDING_MSK;
93	else
94		mask &= ~INT_PENDING_MSK;
95	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
96}
97
98static void altera_mbox_tx_intmask(struct altera_mbox *mbox, bool enable)
99{
100	u32 mask;
101
102	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
103	if (enable)
104		mask |= INT_SPACE_MSK;
105	else
106		mask &= ~INT_SPACE_MSK;
107	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
108}
109
110static bool altera_mbox_is_sender(struct altera_mbox *mbox)
111{
112	u32 reg;
113	/* Write a magic number to PTR register and read back this register.
114	 * This register is read-write if it is a sender.
115	 */
116	#define MBOX_MAGIC	0xA5A5AA55
117	writel_relaxed(MBOX_MAGIC, mbox->mbox_base + MAILBOX_PTR_REG);
118	reg = readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
119	if (reg == MBOX_MAGIC) {
120		/* Clear to 0 */
121		writel_relaxed(0, mbox->mbox_base + MAILBOX_PTR_REG);
122		return true;
123	}
124	return false;
125}
126
127static void altera_mbox_rx_data(struct mbox_chan *chan)
128{
129	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
130	u32 data[2];
131
132	if (altera_mbox_pending(mbox)) {
133		data[MBOX_PTR] =
134			readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
135		data[MBOX_CMD] =
136			readl_relaxed(mbox->mbox_base + MAILBOX_CMD_REG);
137		mbox_chan_received_data(chan, (void *)data);
138	}
139}
140
141static void altera_mbox_poll_rx(unsigned long data)
142{
143	struct mbox_chan *chan = (struct mbox_chan *)data;
144	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
145
146	altera_mbox_rx_data(chan);
147
148	mod_timer(&mbox->rxpoll_timer,
149		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
150}
151
152static irqreturn_t altera_mbox_tx_interrupt(int irq, void *p)
153{
154	struct mbox_chan *chan = (struct mbox_chan *)p;
155	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
156
157	altera_mbox_tx_intmask(mbox, false);
158	mbox_chan_txdone(chan, 0);
159
160	return IRQ_HANDLED;
161}
162
163static irqreturn_t altera_mbox_rx_interrupt(int irq, void *p)
164{
165	struct mbox_chan *chan = (struct mbox_chan *)p;
166
167	altera_mbox_rx_data(chan);
168	return IRQ_HANDLED;
169}
170
171static int altera_mbox_startup_sender(struct mbox_chan *chan)
172{
173	int ret;
174	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
175
176	if (mbox->intr_mode) {
177		ret = request_irq(mbox->irq, altera_mbox_tx_interrupt, 0,
178				  DRIVER_NAME, chan);
179		if (unlikely(ret)) {
180			dev_err(mbox->dev,
181				"failed to register mailbox interrupt:%d\n",
182				ret);
183			return ret;
184		}
185	}
186
187	return 0;
188}
189
190static int altera_mbox_startup_receiver(struct mbox_chan *chan)
191{
192	int ret;
193	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
194
195	if (mbox->intr_mode) {
196		ret = request_irq(mbox->irq, altera_mbox_rx_interrupt, 0,
197				  DRIVER_NAME, chan);
198		if (unlikely(ret)) {
199			mbox->intr_mode = false;
200			goto polling; /* use polling if failed */
201		}
202
203		altera_mbox_rx_intmask(mbox, true);
204		return 0;
205	}
206
207polling:
208	/* Setup polling timer */
209	setup_timer(&mbox->rxpoll_timer, altera_mbox_poll_rx,
210		    (unsigned long)chan);
211	mod_timer(&mbox->rxpoll_timer,
212		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
213
214	return 0;
215}
216
217static int altera_mbox_send_data(struct mbox_chan *chan, void *data)
218{
219	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
220	u32 *udata = (u32 *)data;
221
222	if (!mbox || !data)
223		return -EINVAL;
224	if (!mbox->is_sender) {
225		dev_warn(mbox->dev,
226			 "failed to send. This is receiver mailbox.\n");
227		return -EINVAL;
228	}
229
230	if (altera_mbox_full(mbox))
231		return -EBUSY;
232
233	/* Enable interrupt before send */
234	if (mbox->intr_mode)
235		altera_mbox_tx_intmask(mbox, true);
236
237	/* Pointer register must write before command register */
238	writel_relaxed(udata[MBOX_PTR], mbox->mbox_base + MAILBOX_PTR_REG);
239	writel_relaxed(udata[MBOX_CMD], mbox->mbox_base + MAILBOX_CMD_REG);
240
241	return 0;
242}
243
244static bool altera_mbox_last_tx_done(struct mbox_chan *chan)
245{
246	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
247
248	/* Return false if mailbox is full */
249	return altera_mbox_full(mbox) ? false : true;
250}
251
252static bool altera_mbox_peek_data(struct mbox_chan *chan)
253{
254	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
255
256	return altera_mbox_pending(mbox) ? true : false;
257}
258
259static int altera_mbox_startup(struct mbox_chan *chan)
260{
261	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
262	int ret = 0;
263
264	if (!mbox)
265		return -EINVAL;
266
267	if (mbox->is_sender)
268		ret = altera_mbox_startup_sender(chan);
269	else
270		ret = altera_mbox_startup_receiver(chan);
271
272	return ret;
273}
274
275static void altera_mbox_shutdown(struct mbox_chan *chan)
276{
277	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
278
279	if (mbox->intr_mode) {
280		/* Unmask all interrupt masks */
281		writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
282		free_irq(mbox->irq, chan);
283	} else if (!mbox->is_sender) {
284		del_timer_sync(&mbox->rxpoll_timer);
285	}
286}
287
288static struct mbox_chan_ops altera_mbox_ops = {
289	.send_data = altera_mbox_send_data,
290	.startup = altera_mbox_startup,
291	.shutdown = altera_mbox_shutdown,
292	.last_tx_done = altera_mbox_last_tx_done,
293	.peek_data = altera_mbox_peek_data,
294};
295
296static int altera_mbox_probe(struct platform_device *pdev)
297{
298	struct altera_mbox *mbox;
299	struct resource	*regs;
300	struct mbox_chan *chans;
301	int ret;
302
303	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox),
304			    GFP_KERNEL);
305	if (!mbox)
306		return -ENOMEM;
307
308	/* Allocated one channel */
309	chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
310	if (!chans)
311		return -ENOMEM;
312
313	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
314
315	mbox->mbox_base = devm_ioremap_resource(&pdev->dev, regs);
316	if (IS_ERR(mbox->mbox_base))
317		return PTR_ERR(mbox->mbox_base);
318
319	/* Check is it a sender or receiver? */
320	mbox->is_sender = altera_mbox_is_sender(mbox);
321
322	mbox->irq = platform_get_irq(pdev, 0);
323	if (mbox->irq >= 0)
324		mbox->intr_mode = true;
325
326	mbox->dev = &pdev->dev;
327
328	/* Hardware supports only one channel. */
329	chans[0].con_priv = mbox;
330	mbox->controller.dev = mbox->dev;
331	mbox->controller.num_chans = 1;
332	mbox->controller.chans = chans;
333	mbox->controller.ops = &altera_mbox_ops;
334
335	if (mbox->is_sender) {
336		if (mbox->intr_mode) {
337			mbox->controller.txdone_irq = true;
338		} else {
339			mbox->controller.txdone_poll = true;
340			mbox->controller.txpoll_period = MBOX_POLLING_MS;
341		}
342	}
343
344	ret = mbox_controller_register(&mbox->controller);
345	if (ret) {
346		dev_err(&pdev->dev, "Register mailbox failed\n");
347		goto err;
348	}
349
350	platform_set_drvdata(pdev, mbox);
351err:
352	return ret;
353}
354
355static int altera_mbox_remove(struct platform_device *pdev)
356{
357	struct altera_mbox *mbox = platform_get_drvdata(pdev);
358
359	if (!mbox)
360		return -EINVAL;
361
362	mbox_controller_unregister(&mbox->controller);
363
364	return 0;
365}
366
367static const struct of_device_id altera_mbox_match[] = {
368	{ .compatible = "altr,mailbox-1.0" },
369	{ /* Sentinel */ }
370};
371
372MODULE_DEVICE_TABLE(of, altera_mbox_match);
373
374static struct platform_driver altera_mbox_driver = {
375	.probe	= altera_mbox_probe,
376	.remove	= altera_mbox_remove,
377	.driver	= {
378		.name	= DRIVER_NAME,
379		.of_match_table	= altera_mbox_match,
380	},
381};
382
383module_platform_driver(altera_mbox_driver);
384
385MODULE_LICENSE("GPL v2");
386MODULE_DESCRIPTION("Altera mailbox specific functions");
387MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");
388MODULE_ALIAS("platform:altera-mailbox");
389