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mmc: pwrseq_simple: Add optional reference clock support

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Some WLAN chips attached to a SDIO interface, need a reference clock.

Since this is very common, extend the prseq_simple driver to support
an optional clock that is enabled prior the card power up procedure.

Note: the external clock is optional. Thus an error is not returned
if the clock is not found.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Javier Martinez Canillas 2015-01-29 16:00:06 +01:00 committed by Ulf Hansson
parent 3f656a168c
commit c13045b1e9
1 changed files with 36 additions and 2 deletions
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38
drivers/mmc/core/pwrseq_simple.c
View file

@ -7,6 +7,7 @@
*
* Simple MMC power sequence management
*/
#include <linux/clk.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/device.h>
@ -20,6 +21,8 @@
struct mmc_pwrseq_simple {
struct mmc_pwrseq pwrseq;
bool clk_enabled;
struct clk *ext_clk;
int nr_gpios;
struct gpio_desc *reset_gpios[0];
};
@ -39,6 +42,11 @@ static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
struct mmc_pwrseq_simple, pwrseq);
if (!IS_ERR(pwrseq->ext_clk) && !pwrseq->clk_enabled) {
clk_prepare_enable(pwrseq->ext_clk);
pwrseq->clk_enabled = true;
}
mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
}
@ -50,6 +58,19 @@ static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
}
static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
{
struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
struct mmc_pwrseq_simple, pwrseq);
mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
clk_disable_unprepare(pwrseq->ext_clk);
pwrseq->clk_enabled = false;
}
}
static void mmc_pwrseq_simple_free(struct mmc_host *host)
{
struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
@ -60,6 +81,9 @@ static void mmc_pwrseq_simple_free(struct mmc_host *host)
if (!IS_ERR(pwrseq->reset_gpios[i]))
gpiod_put(pwrseq->reset_gpios[i]);
if (!IS_ERR(pwrseq->ext_clk))
clk_put(pwrseq->ext_clk);
kfree(pwrseq);
host->pwrseq = NULL;
}
@ -67,7 +91,7 @@ static void mmc_pwrseq_simple_free(struct mmc_host *host)
static struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
.pre_power_on = mmc_pwrseq_simple_pre_power_on,
.post_power_on = mmc_pwrseq_simple_post_power_on,
.power_off = mmc_pwrseq_simple_pre_power_on,
.power_off = mmc_pwrseq_simple_power_off,
.free = mmc_pwrseq_simple_free,
};
@ -85,6 +109,13 @@ int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
if (!pwrseq)
return -ENOMEM;
pwrseq->ext_clk = clk_get(dev, "ext_clock");
if (IS_ERR(pwrseq->ext_clk) &&
PTR_ERR(pwrseq->ext_clk) != -ENOENT) {
ret = PTR_ERR(pwrseq->ext_clk);
goto free;
}
for (i = 0; i < nr_gpios; i++) {
pwrseq->reset_gpios[i] = gpiod_get_index(dev, "reset", i,
GPIOD_OUT_HIGH);
@ -96,7 +127,7 @@ int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
while (--i)
gpiod_put(pwrseq->reset_gpios[i]);
goto free;
goto clk_put;
}
}
@ -105,6 +136,9 @@ int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
host->pwrseq = &pwrseq->pwrseq;
return 0;
clk_put:
if (!IS_ERR(pwrseq->ext_clk))
clk_put(pwrseq->ext_clk);
free:
kfree(pwrseq);
return ret;