[RFC 2/2] mmc: core: Add support for power sequences

Ulf Hansson
2014-06-19T13:05:44Z

The MMC subsystem uses a discoverable bus which sometimes means the
power sequences to enable power to the card, is far too complex to be
handled through the regular ->set_ios() callback.

To adress these scenarios, we try to fetch a pwrseq method while
parsing the common MMC DT bindings. If a such method is found we select
the corresponding state for it from mmc_power_up|off().

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
drivers/mmc/core/core.c | 7 +++++++
drivers/mmc/core/host.c | 5 +++++
include/linux/mmc/host.h | 3 +++
3 files changed, 15 insertions(+)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 7dc0c85..46558b5 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -29,6 +29,7 @@
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/of.h>
+#include <linux/pwrseq.h>

#include <linux/mmc/card.h>
#include <linux/mmc/host.h>
@@ -1533,6 +1534,9 @@ void mmc_power_up(struct mmc_host *host, u32 ocr)

mmc_host_clk_hold(host);

+ if (!IS_ERR(host->pwrseq))
+ pwrseq_select_state(host->pwrseq, PWRSEQ_POWER_ON);
+
host->ios.vdd = fls(ocr) - 1;
if (mmc_host_is_spi(host))
host->ios.chip_select = MMC_CS_HIGH;
@@ -1591,6 +1595,9 @@ void mmc_power_off(struct mmc_host *host)
host->ios.timing = MMC_TIMING_LEGACY;
mmc_set_ios(host);

+ if (!IS_ERR(host->pwrseq))
+ pwrseq_select_state(host->pwrseq, PWRSEQ_POWER_OFF);
+
/*
* Some configurations, such as the 802.11 SDIO card in the OLPC
* XO-1.5, require a short delay after poweroff before the card
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 95cceae..fdf8596 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -22,6 +22,7 @@
#include <linux/leds.h>
#include <linux/slab.h>
#include <linux/suspend.h>
+#include <linux/pwrseq.h>

#include <linux/mmc/host.h>
#include <linux/mmc/card.h>
@@ -317,6 +318,10 @@ int mmc_of_parse(struct mmc_host *host)
if (!host->parent || !host->parent->of_node)
return 0;

+ host->pwrseq = devm_pwrseq_get_optional(host->parent);
+ if (IS_ERR(host->pwrseq))
+ return PTR_ERR(host->pwrseq);
+
np = host->parent->of_node;

/* "bus-width" is translated to MMC_CAP_*_BIT_DATA flags */
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 7960424..306b78c 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -195,9 +195,12 @@ struct mmc_supply {
struct regulator *vqmmc; /* Optional Vccq supply */
};

+struct pwrseq;
+
struct mmc_host {
struct device *parent;
struct device class_dev;
+ struct pwrseq *pwrseq;
int index;
const struct mmc_host_ops *ops;
unsigned int f_min;
--
1.7.9.5