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@xxxxxx>
---
v2: switch to use snprintf()
Hi Chris
On Sat, 24 Dec 2011, Chris Ball wrote:
> > +int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio,
> > + unsigned int irq, unsigned long flags)
> > +{
> > + size_t len = strlen(dev_name(host->parent)) + 4;
> > + struct mmc_cd_gpio *cd = kmalloc(sizeof(*cd) + len, GFP_KERNEL);
> > + int ret;
> > +
> > + if (!cd)
> > + return -ENOMEM;
> > +
> > + sprintf(cd->label, "%s cd", dev_name(host->parent));
>
> Mind using snprintf() instead? I prefer it for new uses, it leaves
> fewer uses of sprintf to audit for correctness.
I don't think it's needed here - I allocate exactly the required number of
bytes, but, as you mention, it should help us, humans, feel more secure
about it:-)
drivers/mmc/core/Makefile | 2 +-
drivers/mmc/core/cd-gpio.c | 74 +++++++++++++++++++++++++++++++++++++++++++
include/linux/mmc/cd-gpio.h | 19 +++++++++++
3 files changed, 94 insertions(+), 1 deletions(-)
create mode 100644 drivers/mmc/core/cd-gpio.c
create mode 100644 include/linux/mmc/cd-gpio.h
diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile
index 6395019..dca4428 100644
--- a/drivers/mmc/core/Makefile
+++ b/drivers/mmc/core/Makefile
@@ -7,6 +7,6 @@ mmc_core-y := core.o bus.o host.o \
mmc.o mmc_ops.o sd.o sd_ops.o \
sdio.o sdio_ops.o sdio_bus.o \
sdio_cis.o sdio_io.o sdio_irq.o \
- quirks.o
+ quirks.o cd-gpio.o
mmc_core-$(CONFIG_DEBUG_FS) += debugfs.o
diff --git a/drivers/mmc/core/cd-gpio.c b/drivers/mmc/core/cd-gpio.c
new file mode 100644
index 0000000..4c79f0c
--- /dev/null
+++ b/drivers/mmc/core/cd-gpio.c
@@ -0,0 +1,74 @@
+/*
+ * Generic GPIO card-detect helper
+ *
+ * Copyright (C) 2011, Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/mmc/host.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+struct mmc_cd_gpio {
+ unsigned int gpio;
+ char label[0];
+};
+
+static irqreturn_t mmc_cd_gpio_irqt(int irq, void *dev_id)
+{
+ /* Schedule a card detection after a debounce timeout */
+ mmc_detect_change(dev_id, msecs_to_jiffies(100));
+ return IRQ_HANDLED;
+}
+
+int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio,
+ unsigned int irq, unsigned long flags)
+{
+ size_t len = strlen(dev_name(host->parent)) + 4;
+ struct mmc_cd_gpio *cd = kmalloc(sizeof(*cd) + len, GFP_KERNEL);
+ int ret;
+
+ if (!cd)
+ return -ENOMEM;
+
+ snprintf(cd->label, len, "%s cd", dev_name(host->parent));
+
+ ret = gpio_request_one(gpio, GPIOF_DIR_IN, cd->label);
+ if (ret < 0)
+ goto egpioreq;
+
+ ret = request_threaded_irq(irq, NULL, mmc_cd_gpio_irqt,
+ flags, cd->label, host);
+ if (ret < 0)
+ goto eirqreq;
+
+ cd->gpio = gpio;
+ host->hotplug.irq = irq;
+ host->hotplug.handler_priv = cd;
+
+ return 0;
+
+eirqreq:
+ gpio_free(gpio);
+egpioreq:
+ kfree(cd);
+ return ret;
+}
+EXPORT_SYMBOL(mmc_cd_gpio_request);
+
+void mmc_cd_gpio_free(struct mmc_host *host)
+{
+ struct mmc_cd_gpio *cd = host->hotplug.handler_priv;
+
+ free_irq(host->hotplug.irq, host);
+ gpio_free(cd->gpio);
+ kfree(cd);
+}
+EXPORT_SYMBOL(mmc_cd_gpio_free);
diff --git a/include/linux/mmc/cd-gpio.h b/include/linux/mmc/cd-gpio.h
new file mode 100644
index 0000000..a8e4697
--- /dev/null
+++ b/include/linux/mmc/cd-gpio.h
@@ -0,0 +1,19 @@
+/*
+ * Generic GPIO card-detect helper header
+ *
+ * Copyright (C) 2011, Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef MMC_CD_GPIO_H
+#define MMC_CD_GPIO_H
+
+struct mmc_host;
+int mmc_cd_gpio_request(struct mmc_host *host, unsigned int gpio,
+ unsigned int irq, unsigned long flags);
+void mmc_cd_gpio_free(struct mmc_host *host);
+
+#endif
--
1.7.2.5
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