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80 lines
2.8 KiB
Diff
80 lines
2.8 KiB
Diff
From f6d983b7bc9ae79d0eb4dea7bc30a1ad5ff428a7 Mon Sep 17 00:00:00 2001
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From: Linus Walleij <linus.walleij@linaro.org>
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Date: Fri, 12 Oct 2018 14:54:12 +0200
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Subject: [PATCH 802/806] regulator/gpio: Allow nonexclusive GPIO access
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commit b0ce7b29bfcd090ddba476f45a75ec0a797b048a upstream.
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[ This is a partial cherry-pick, omitting the regulator
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change which isn't required ]
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This allows nonexclusive (simultaneous) access to a single
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GPIO line for the fixed regulator enable line. This happens
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when several regulators use the same GPIO for enabling and
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disabling a regulator, and all need a handle on their GPIO
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descriptor.
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This solution with a special flag is not entirely elegant
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and should ideally be replaced by something more careful as
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this makes it possible for several consumers to
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enable/disable the same GPIO line to the left and right
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without any consistency. The current use inside the regulator
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core should however be fine as it takes special care to
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handle this.
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For the state of the GPIO backend, this is still the
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lesser evil compared to going back to global GPIO
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numbers.
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Cc: Marek Szyprowski <m.szyprowski@samsung.com>
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Cc: Jon Hunter <jonathanh@nvidia.com>
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Fixes: efdfeb079cc3 ("regulator: fixed: Convert to use GPIO descriptor only")
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Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
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Tested-by: Jon Hunter <jonathanh@nvidia.com>
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Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
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Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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Signed-off-by: Mark Brown <broonie@kernel.org>
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---
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drivers/gpio/gpiolib.c | 19 +++++++++++++++++--
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include/linux/gpio/consumer.h | 1 +
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2 files changed, 18 insertions(+), 2 deletions(-)
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--- a/drivers/gpio/gpiolib.c
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+++ b/drivers/gpio/gpiolib.c
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@@ -3979,8 +3979,23 @@ struct gpio_desc *__must_check gpiod_get
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* the device name as label
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*/
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status = gpiod_request(desc, con_id ? con_id : devname);
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- if (status < 0)
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- return ERR_PTR(status);
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+ if (status < 0) {
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+ if (status == -EBUSY && flags & GPIOD_FLAGS_BIT_NONEXCLUSIVE) {
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+ /*
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+ * This happens when there are several consumers for
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+ * the same GPIO line: we just return here without
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+ * further initialization. It is a bit if a hack.
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+ * This is necessary to support fixed regulators.
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+ *
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+ * FIXME: Make this more sane and safe.
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+ */
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+ dev_info(dev, "nonexclusive access to GPIO for %s\n",
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+ con_id ? con_id : devname);
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+ return desc;
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+ } else {
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+ return ERR_PTR(status);
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+ }
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+ }
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status = gpiod_configure_flags(desc, con_id, lookupflags, flags);
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if (status < 0) {
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--- a/include/linux/gpio/consumer.h
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+++ b/include/linux/gpio/consumer.h
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@@ -30,6 +30,7 @@ struct gpio_descs {
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#define GPIOD_FLAGS_BIT_DIR_OUT BIT(1)
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#define GPIOD_FLAGS_BIT_DIR_VAL BIT(2)
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#define GPIOD_FLAGS_BIT_OPEN_DRAIN BIT(3)
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+#define GPIOD_FLAGS_BIT_NONEXCLUSIVE BIT(4)
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/**
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* Optional flags that can be passed to one of gpiod_* to configure direction
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