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mmc: pwrseq-simple: Add an optional post-power-on-delay

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Some devices need a while to boot their firmware after providing clks /
de-asserting resets before they are ready to receive sdio commands.

This commits adds a post-power-on-delay-ms devicetree property to
mmc-pwrseq-simple for use with such devices.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Hans de Goede 2016-08-07 21:02:38 +02:00 committed by Ulf Hansson
parent 4cbc6dbd52
commit 721e049717
2 changed files with 11 additions and 0 deletions
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2
Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt
View file

@ -16,6 +16,8 @@ Optional properties:
See ../clocks/clock-bindings.txt for details.
- clock-names : Must include the following entry:
"ext_clock" (External clock provided to the card).
- post-power-on-delay-ms : Delay in ms after powering the card and
de-asserting the reset-gpios (if any)
Example:

9
drivers/mmc/core/pwrseq_simple.c
View file

@ -16,6 +16,8 @@
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/delay.h>
#include <linux/property.h>
#include <linux/mmc/host.h>
@ -24,6 +26,7 @@
struct mmc_pwrseq_simple {
struct mmc_pwrseq pwrseq;
bool clk_enabled;
u32 post_power_on_delay_ms;
struct clk *ext_clk;
struct gpio_descs *reset_gpios;
};
@ -64,6 +67,9 @@ static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
if (pwrseq->post_power_on_delay_ms)
msleep(pwrseq->post_power_on_delay_ms);
}
static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
@ -111,6 +117,9 @@ static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
return PTR_ERR(pwrseq->reset_gpios);
}
device_property_read_u32(dev, "post-power-on-delay-ms",
&pwrseq->post_power_on_delay_ms);
pwrseq->pwrseq.dev = dev;
pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
pwrseq->pwrseq.owner = THIS_MODULE;