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90 lines
2.8 KiB
Diff
90 lines
2.8 KiB
Diff
From: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
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Date: Mon, 28 Apr 2008 09:14:44 +0000 (-0700)
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Subject: gpiolib: better rmmod infrastructure
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X-Git-Tag: v2.6.26-rc1~851
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=438d8908b379b6322fc3b28d45c9ebdddf58bc20
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gpiolib: better rmmod infrastructure
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As long as one or more GPIOs on a gpio chip are used its driver should not be
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unloaded. The existing mechanism (gpiochip_remove failure) doesn't address
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that, since rmmod can no longer be made to fail by having the cleanup code
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report errors. Module usecounts are the solution.
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Assuming standard "initialize struct to zero" policies, this change won't
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affect SOC platform drivers. However, drivers for external chips (on I2C and
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SPI busses) should be updated if they can be built as modules.
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Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
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[ gpio_ensure_requested() needs to update module usecounts too ]
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Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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--- a/drivers/gpio/gpiolib.c
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+++ b/drivers/gpio/gpiolib.c
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@@ -68,6 +68,9 @@ static void gpio_ensure_requested(struct
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if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
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pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc));
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desc_set_label(desc, "[auto]");
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+ if (!try_module_get(desc->chip->owner))
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+ pr_err("GPIO-%d: module can't be gotten \n",
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+ (int)(desc - gpio_desc));
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}
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}
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@@ -177,6 +180,9 @@ int gpio_request(unsigned gpio, const ch
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if (desc->chip == NULL)
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goto done;
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+ if (!try_module_get(desc->chip->owner))
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+ goto done;
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+
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/* NOTE: gpio_request() can be called in early boot,
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* before IRQs are enabled.
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*/
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@@ -184,8 +190,10 @@ int gpio_request(unsigned gpio, const ch
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if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
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desc_set_label(desc, label ? : "?");
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status = 0;
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- } else
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+ } else {
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status = -EBUSY;
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+ module_put(desc->chip->owner);
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+ }
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done:
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if (status)
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@@ -209,9 +217,10 @@ void gpio_free(unsigned gpio)
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spin_lock_irqsave(&gpio_lock, flags);
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desc = &gpio_desc[gpio];
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- if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags))
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+ if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags)) {
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desc_set_label(desc, NULL);
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- else
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+ module_put(desc->chip->owner);
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+ } else
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WARN_ON(extra_checks);
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spin_unlock_irqrestore(&gpio_lock, flags);
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--- a/include/asm-generic/gpio.h
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+++ b/include/asm-generic/gpio.h
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@@ -17,6 +17,7 @@
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#endif
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struct seq_file;
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+struct module;
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/**
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* struct gpio_chip - abstract a GPIO controller
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@@ -48,6 +49,7 @@ struct seq_file;
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*/
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struct gpio_chip {
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char *label;
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+ struct module *owner;
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int (*direction_input)(struct gpio_chip *chip,
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unsigned offset);
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