![Guennadi Liakhovetski](/assets/img/avatar_default.png)
Card Write-Protect pin is often implemented, using a GPIO, which makes it simple to provide a generic handler for it. Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de> Signed-off-by: Chris Ball <cjb@laptop.org>
189 lines
4.1 KiB
C
189 lines
4.1 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/mmc/slot-gpio.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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struct mmc_gpio {
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int ro_gpio;
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int cd_gpio;
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char *ro_label;
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char cd_label[0];
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};
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static irqreturn_t mmc_gpio_cd_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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static int mmc_gpio_alloc(struct mmc_host *host)
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{
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size_t len = strlen(dev_name(host->parent)) + 4;
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struct mmc_gpio *ctx;
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mutex_lock(&host->slot.lock);
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ctx = host->slot.handler_priv;
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if (!ctx) {
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/*
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* devm_kzalloc() can be called after device_initialize(), even
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* before device_add(), i.e., between mmc_alloc_host() and
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* mmc_add_host()
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*/
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ctx = devm_kzalloc(&host->class_dev, sizeof(*ctx) + 2 * len,
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GFP_KERNEL);
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if (ctx) {
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ctx->ro_label = ctx->cd_label + len;
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snprintf(ctx->cd_label, len, "%s cd", dev_name(host->parent));
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snprintf(ctx->ro_label, len, "%s ro", dev_name(host->parent));
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ctx->cd_gpio = -EINVAL;
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ctx->ro_gpio = -EINVAL;
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host->slot.handler_priv = ctx;
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}
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}
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mutex_unlock(&host->slot.lock);
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return ctx ? 0 : -ENOMEM;
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}
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int mmc_gpio_get_ro(struct mmc_host *host)
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{
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struct mmc_gpio *ctx = host->slot.handler_priv;
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if (!ctx || !gpio_is_valid(ctx->ro_gpio))
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return -ENOSYS;
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return !gpio_get_value_cansleep(ctx->ro_gpio) ^
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!!(host->caps2 & MMC_CAP2_RO_ACTIVE_HIGH);
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}
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EXPORT_SYMBOL(mmc_gpio_get_ro);
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int mmc_gpio_get_cd(struct mmc_host *host)
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{
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struct mmc_gpio *ctx = host->slot.handler_priv;
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if (!ctx || !gpio_is_valid(ctx->cd_gpio))
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return -ENOSYS;
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return !gpio_get_value_cansleep(ctx->cd_gpio) ^
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!!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
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}
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EXPORT_SYMBOL(mmc_gpio_get_cd);
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int mmc_gpio_request_ro(struct mmc_host *host, unsigned int gpio)
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{
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struct mmc_gpio *ctx;
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int ret;
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if (!gpio_is_valid(gpio))
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return -EINVAL;
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ret = mmc_gpio_alloc(host);
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if (ret < 0)
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return ret;
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ctx = host->slot.handler_priv;
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return gpio_request_one(gpio, GPIOF_DIR_IN, ctx->ro_label);
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}
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EXPORT_SYMBOL(mmc_gpio_request_ro);
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int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio)
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{
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struct mmc_gpio *ctx;
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int irq = gpio_to_irq(gpio);
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int ret;
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ret = mmc_gpio_alloc(host);
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if (ret < 0)
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return ret;
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ctx = host->slot.handler_priv;
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ret = gpio_request_one(gpio, GPIOF_DIR_IN, ctx->cd_label);
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if (ret < 0)
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/*
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* don't bother freeing memory. It might still get used by other
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* slot functions, in any case it will be freed, when the device
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* is destroyed.
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*/
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return ret;
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/*
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* Even if gpio_to_irq() returns a valid IRQ number, the platform might
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* still prefer to poll, e.g., because that IRQ number is already used
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* by another unit and cannot be shared.
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*/
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if (irq >= 0 && host->caps & MMC_CAP_NEEDS_POLL)
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irq = -EINVAL;
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if (irq >= 0) {
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ret = request_threaded_irq(irq, NULL, mmc_gpio_cd_irqt,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
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ctx->cd_label, host);
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if (ret < 0)
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irq = ret;
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}
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host->slot.cd_irq = irq;
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if (irq < 0)
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host->caps |= MMC_CAP_NEEDS_POLL;
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ctx->cd_gpio = gpio;
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return 0;
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}
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EXPORT_SYMBOL(mmc_gpio_request_cd);
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void mmc_gpio_free_ro(struct mmc_host *host)
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{
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struct mmc_gpio *ctx = host->slot.handler_priv;
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int gpio;
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if (!ctx || !gpio_is_valid(ctx->ro_gpio))
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return;
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gpio = ctx->ro_gpio;
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ctx->ro_gpio = -EINVAL;
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gpio_free(gpio);
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}
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EXPORT_SYMBOL(mmc_gpio_free_ro);
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void mmc_gpio_free_cd(struct mmc_host *host)
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{
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struct mmc_gpio *ctx = host->slot.handler_priv;
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int gpio;
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if (!ctx || !gpio_is_valid(ctx->cd_gpio))
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return;
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if (host->slot.cd_irq >= 0) {
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free_irq(host->slot.cd_irq, host);
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host->slot.cd_irq = -EINVAL;
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}
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gpio = ctx->cd_gpio;
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ctx->cd_gpio = -EINVAL;
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gpio_free(gpio);
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}
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EXPORT_SYMBOL(mmc_gpio_free_cd);
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