xref: /openbmc/linux/drivers/mmc/core/sdio_irq.c (revision 9ac8d3fb) 
1 /*
2  * linux/drivers/mmc/core/sdio_irq.c
3  *
4  * Author:      Nicolas Pitre
5  * Created:     June 18, 2007
6  * Copyright:   MontaVista Software Inc.
7  *
8  * Copyright 2008 Pierre Ossman
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or (at
13  * your option) any later version.
14  */
15 
16 #include <linux/kernel.h>
17 #include <linux/sched.h>
18 #include <linux/kthread.h>
19 #include <linux/wait.h>
20 #include <linux/delay.h>
21 
22 #include <linux/mmc/core.h>
23 #include <linux/mmc/host.h>
24 #include <linux/mmc/card.h>
25 #include <linux/mmc/sdio.h>
26 #include <linux/mmc/sdio_func.h>
27 
28 #include "sdio_ops.h"
29 
30 static int process_sdio_pending_irqs(struct mmc_card *card)
31 {
32 	int i, ret, count;
33 	unsigned char pending;
34 
35 	ret = mmc_io_rw_direct(card, 0, 0, SDIO_CCCR_INTx, 0, &pending);
36 	if (ret) {
37 		printk(KERN_DEBUG "%s: error %d reading SDIO_CCCR_INTx\n",
38 		       mmc_card_id(card), ret);
39 		return ret;
40 	}
41 
42 	count = 0;
43 	for (i = 1; i <= 7; i++) {
44 		if (pending & (1 << i)) {
45 			struct sdio_func *func = card->sdio_func[i - 1];
46 			if (!func) {
47 				printk(KERN_WARNING "%s: pending IRQ for "
48 					"non-existant function\n",
49 					mmc_card_id(card));
50 				ret = -EINVAL;
51 			} else if (func->irq_handler) {
52 				func->irq_handler(func);
53 				count++;
54 			} else {
55 				printk(KERN_WARNING "%s: pending IRQ with no handler\n",
56 				       sdio_func_id(func));
57 				ret = -EINVAL;
58 			}
59 		}
60 	}
61 
62 	if (count)
63 		return count;
64 
65 	return ret;
66 }
67 
68 static int sdio_irq_thread(void *_host)
69 {
70 	struct mmc_host *host = _host;
71 	struct sched_param param = { .sched_priority = 1 };
72 	unsigned long period, idle_period;
73 	int ret;
74 
75 	sched_setscheduler(current, SCHED_FIFO, &param);
76 
77 	/*
78 	 * We want to allow for SDIO cards to work even on non SDIO
79 	 * aware hosts.  One thing that non SDIO host cannot do is
80 	 * asynchronous notification of pending SDIO card interrupts
81 	 * hence we poll for them in that case.
82 	 */
83 	idle_period = msecs_to_jiffies(10);
84 	period = (host->caps & MMC_CAP_SDIO_IRQ) ?
85 		MAX_SCHEDULE_TIMEOUT : idle_period;
86 
87 	pr_debug("%s: IRQ thread started (poll period = %lu jiffies)\n",
88 		 mmc_hostname(host), period);
89 
90 	do {
91 		/*
92 		 * We claim the host here on drivers behalf for a couple
93 		 * reasons:
94 		 *
95 		 * 1) it is already needed to retrieve the CCCR_INTx;
96 		 * 2) we want the driver(s) to clear the IRQ condition ASAP;
97 		 * 3) we need to control the abort condition locally.
98 		 *
99 		 * Just like traditional hard IRQ handlers, we expect SDIO
100 		 * IRQ handlers to be quick and to the point, so that the
101 		 * holding of the host lock does not cover too much work
102 		 * that doesn't require that lock to be held.
103 		 */
104 		ret = __mmc_claim_host(host, &host->sdio_irq_thread_abort);
105 		if (ret)
106 			break;
107 		ret = process_sdio_pending_irqs(host->card);
108 		mmc_release_host(host);
109 
110 		/*
111 		 * Give other threads a chance to run in the presence of
112 		 * errors.
113 		 */
114 		if (ret < 0) {
115 			set_current_state(TASK_INTERRUPTIBLE);
116 			if (!kthread_should_stop())
117 				schedule_timeout(HZ);
118 			set_current_state(TASK_RUNNING);
119 		}
120 
121 		/*
122 		 * Adaptive polling frequency based on the assumption
123 		 * that an interrupt will be closely followed by more.
124 		 * This has a substantial benefit for network devices.
125 		 */
126 		if (!(host->caps & MMC_CAP_SDIO_IRQ)) {
127 			if (ret > 0)
128 				period /= 2;
129 			else {
130 				period++;
131 				if (period > idle_period)
132 					period = idle_period;
133 			}
134 		}
135 
136 		set_current_state(TASK_INTERRUPTIBLE);
137 		if (host->caps & MMC_CAP_SDIO_IRQ)
138 			host->ops->enable_sdio_irq(host, 1);
139 		if (!kthread_should_stop())
140 			schedule_timeout(period);
141 		set_current_state(TASK_RUNNING);
142 	} while (!kthread_should_stop());
143 
144 	if (host->caps & MMC_CAP_SDIO_IRQ)
145 		host->ops->enable_sdio_irq(host, 0);
146 
147 	pr_debug("%s: IRQ thread exiting with code %d\n",
148 		 mmc_hostname(host), ret);
149 
150 	return ret;
151 }
152 
153 static int sdio_card_irq_get(struct mmc_card *card)
154 {
155 	struct mmc_host *host = card->host;
156 
157 	WARN_ON(!host->claimed);
158 
159 	if (!host->sdio_irqs++) {
160 		atomic_set(&host->sdio_irq_thread_abort, 0);
161 		host->sdio_irq_thread =
162 			kthread_run(sdio_irq_thread, host, "ksdioirqd/%s",
163 				mmc_hostname(host));
164 		if (IS_ERR(host->sdio_irq_thread)) {
165 			int err = PTR_ERR(host->sdio_irq_thread);
166 			host->sdio_irqs--;
167 			return err;
168 		}
169 	}
170 
171 	return 0;
172 }
173 
174 static int sdio_card_irq_put(struct mmc_card *card)
175 {
176 	struct mmc_host *host = card->host;
177 
178 	WARN_ON(!host->claimed);
179 	BUG_ON(host->sdio_irqs < 1);
180 
181 	if (!--host->sdio_irqs) {
182 		atomic_set(&host->sdio_irq_thread_abort, 1);
183 		kthread_stop(host->sdio_irq_thread);
184 	}
185 
186 	return 0;
187 }
188 
189 /**
190  *	sdio_claim_irq - claim the IRQ for a SDIO function
191  *	@func: SDIO function
192  *	@handler: IRQ handler callback
193  *
194  *	Claim and activate the IRQ for the given SDIO function. The provided
195  *	handler will be called when that IRQ is asserted.  The host is always
196  *	claimed already when the handler is called so the handler must not
197  *	call sdio_claim_host() nor sdio_release_host().
198  */
199 int sdio_claim_irq(struct sdio_func *func, sdio_irq_handler_t *handler)
200 {
201 	int ret;
202 	unsigned char reg;
203 
204 	BUG_ON(!func);
205 	BUG_ON(!func->card);
206 
207 	pr_debug("SDIO: Enabling IRQ for %s...\n", sdio_func_id(func));
208 
209 	if (func->irq_handler) {
210 		pr_debug("SDIO: IRQ for %s already in use.\n", sdio_func_id(func));
211 		return -EBUSY;
212 	}
213 
214 	ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
215 	if (ret)
216 		return ret;
217 
218 	reg |= 1 << func->num;
219 
220 	reg |= 1; /* Master interrupt enable */
221 
222 	ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IENx, reg, NULL);
223 	if (ret)
224 		return ret;
225 
226 	func->irq_handler = handler;
227 	ret = sdio_card_irq_get(func->card);
228 	if (ret)
229 		func->irq_handler = NULL;
230 
231 	return ret;
232 }
233 EXPORT_SYMBOL_GPL(sdio_claim_irq);
234 
235 /**
236  *	sdio_release_irq - release the IRQ for a SDIO function
237  *	@func: SDIO function
238  *
239  *	Disable and release the IRQ for the given SDIO function.
240  */
241 int sdio_release_irq(struct sdio_func *func)
242 {
243 	int ret;
244 	unsigned char reg;
245 
246 	BUG_ON(!func);
247 	BUG_ON(!func->card);
248 
249 	pr_debug("SDIO: Disabling IRQ for %s...\n", sdio_func_id(func));
250 
251 	if (func->irq_handler) {
252 		func->irq_handler = NULL;
253 		sdio_card_irq_put(func->card);
254 	}
255 
256 	ret = mmc_io_rw_direct(func->card, 0, 0, SDIO_CCCR_IENx, 0, &reg);
257 	if (ret)
258 		return ret;
259 
260 	reg &= ~(1 << func->num);
261 
262 	/* Disable master interrupt with the last function interrupt */
263 	if (!(reg & 0xFE))
264 		reg = 0;
265 
266 	ret = mmc_io_rw_direct(func->card, 1, 0, SDIO_CCCR_IENx, reg, NULL);
267 	if (ret)
268 		return ret;
269 
270 	return 0;
271 }
272 EXPORT_SYMBOL_GPL(sdio_release_irq);
273 
274