349ab52446
This patch adds a primitive helper to support card hotplug detection on platforms, where a GPIO, capable of producing interrupts, is used for detection of card-insertion and -removal events. Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de> Signed-off-by: Chris Ball <cjb@laptop.org>
74 lines
1.6 KiB
C
74 lines
1.6 KiB
C
/*
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* Generic GPIO card-detect helper
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*
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* Copyright (C) 2011, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/err.h>
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#include <linux/gpio.h>
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#include <linux/interrupt.h>
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#include <linux/jiffies.h>
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#include <linux/mmc/host.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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struct mmc_cd_gpio {
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unsigned int gpio;
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char label[0];
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};
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static irqreturn_t mmc_cd_gpio_irqt(int irq, void *dev_id)
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{
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/* Schedule a card detection after a debounce timeout */
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mmc_detect_change(dev_id, msecs_to_jiffies(100));
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return IRQ_HANDLED;
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}
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int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio,
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unsigned int irq, unsigned long flags)
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{
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size_t len = strlen(dev_name(host->parent)) + 4;
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struct mmc_cd_gpio *cd = kmalloc(sizeof(*cd) + len, GFP_KERNEL);
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int ret;
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if (!cd)
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return -ENOMEM;
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snprintf(cd->label, len, "%s cd", dev_name(host->parent));
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ret = gpio_request_one(gpio, GPIOF_DIR_IN, cd->label);
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if (ret < 0)
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goto egpioreq;
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ret = request_threaded_irq(irq, NULL, mmc_cd_gpio_irqt,
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flags, cd->label, host);
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if (ret < 0)
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goto eirqreq;
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cd->gpio = gpio;
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host->hotplug.irq = irq;
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host->hotplug.handler_priv = cd;
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return 0;
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eirqreq:
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gpio_free(gpio);
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egpioreq:
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kfree(cd);
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return ret;
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}
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EXPORT_SYMBOL(mmc_cd_gpio_request);
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void mmc_cd_gpio_free(struct mmc_host *host)
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{
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struct mmc_cd_gpio *cd = host->hotplug.handler_priv;
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free_irq(host->hotplug.irq, host);
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gpio_free(cd->gpio);
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kfree(cd);
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}
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EXPORT_SYMBOL(mmc_cd_gpio_free);
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