[PATCH V4 0/4] mmc: core: Add support for MMC power sequences

[PATCH V4 0/4] mmc: core: Add support for MMC power sequences

[Ulf Hansson]

Changes in v4:
	- Fixed call to kfree() in patch3 and patch4.

Changes in v3:
	Fixed comments from Mark Rutland:
	- Document binding in one patch to get the big picture.
	- Keep code and DT document consistent around how many GPIO resets we
	  support. I decided to go for one GPIO, we can extend that if needed
	  later on.
	- Change compatible string for simple MMC power sequence and renamed the
	  file for its documentation.
	- Updated commit messages according to above changes.

Changes in v2:
	Fixed comments from Russell King:
	- Renamed pwrseq callbacks and corresponding interface functions.
	- Move the call to the previous namned ->power_on() callback, to the
	  end of mmc_power_up() to get consistent behavior.


This is yet another try to solve the issues of dealing with power sequences for
the MMC subsystem. The latest attempt, see link below, took a generic approach
by adding a new top level driver layer. That's was rejected by several reasons.
http://lwn.net/Articles/602855/

This time the approach is focused to fix the issues for MMC only.

To give a short background, SOCs may specify a specific MMC power sequence. To
successfully detect an (e)MMC/SD/SDIO card, that power sequence must be followed
while initializing the card.

To be able to handle these SOC specific power sequences, we add a MMC power
sequence interface, which helps the mmc core to deal with such.

A MMC power sequence provider then implements a set of callbacks from the above
mentioned interface. The provider has a corresponding DT compatibility string
and relies on CONFIG_OF to be set to find it's various resourses, like for
example a GPIO reset.

The mmc core will from mmc_of_parse() try find a "mmc-pwrseq" DT node and then
call the corresponding MMC power sequence provider's initialization function.


Ulf Hansson (4):
  mmc: core: Initial support for MMC power sequences
  mmc: pwrseq: Document DT bindings for the simple MMC power sequence
  mmc: pwrseq: Initial support for the simple MMC power sequence
    provider
  mmc: pwrseq_simple: Add support for a reset GPIO pin

 .../devicetree/bindings/mmc/mmc-pwrseq-simple.txt  |  20 ++++
 Documentation/devicetree/bindings/mmc/mmc.txt      |  14 +++
 drivers/mmc/core/Makefile                          |   2 +-
 drivers/mmc/core/core.c                            |   7 ++
 drivers/mmc/core/host.c                            |   4 +-
 drivers/mmc/core/pwrseq.c                          | 109 +++++++++++++++++++++
 drivers/mmc/core/pwrseq.h                          |  42 ++++++++
 drivers/mmc/core/pwrseq_simple.c                   |  86 ++++++++++++++++
 include/linux/mmc/host.h                           |   2 +
 9 files changed, 284 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt
 create mode 100644 drivers/mmc/core/pwrseq.c
 create mode 100644 drivers/mmc/core/pwrseq.h
 create mode 100644 drivers/mmc/core/pwrseq_simple.c

-- 
1.9.1

[PATCH V4 1/4] mmc: core: Initial support for MMC power sequences

[Ulf Hansson]

System on chip designs may specify a specific MMC power sequence. To
successfully detect an (e)MMC/SD/SDIO card, that power sequence must
be followed while initializing the card.

To be able to handle these SOC specific power sequences, let's add a
MMC power sequence interface. It provides the following functions to
help the mmc core to deal with these power sequences.

mmc_pwrseq_alloc() - Invoked from mmc_of_parse(), to initialize data.
mmc_pwrseq_pre_power_on()- Invoked in the beginning of mmc_power_up().
mmc_pwrseq_post_power_on()- Invoked at the end in mmc_power_up().
mmc_pwrseq_power_off()- Invoked from mmc_power_off().
mmc_pwrseq_free() - Invoked from mmc_free_host(), to free data.

Each MMC power sequence provider will be responsible to implement a set
of callbacks. These callbacks mirrors the functions above.

This patch adds the skeleton, following patches will extend the core of
the MMC power sequence and add support for a specific simple MMC power
sequence.

Do note, since the mmc_pwrseq_alloc() is invoked from mmc_of_parse(),
host drivers needs to make use of this API to enable the support for
MMC power sequences. Moreover the MMC power sequence support depends on
CONFIG_OF.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changes in v4:
	- None.

---
 drivers/mmc/core/Makefile |  2 +-
 drivers/mmc/core/core.c   |  7 +++++++
 drivers/mmc/core/host.c   |  4 +++-
 drivers/mmc/core/pwrseq.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/mmc/core/pwrseq.h | 40 +++++++++++++++++++++++++++++++++++++
 include/linux/mmc/host.h  |  2 ++
 6 files changed, 103 insertions(+), 2 deletions(-)
 create mode 100644 drivers/mmc/core/pwrseq.c
 create mode 100644 drivers/mmc/core/pwrseq.h

diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile
index 38ed210..ccdd35f 100644
--- a/drivers/mmc/core/Makefile
+++ b/drivers/mmc/core/Makefile
@@ -8,5 +8,5 @@ mmc_core-y			:= core.o bus.o host.o \
 				   sdio.o sdio_ops.o sdio_bus.o \
 				   sdio_cis.o sdio_io.o sdio_irq.o \
 				   quirks.o slot-gpio.o
-
+mmc_core-$(CONFIG_OF)		+= pwrseq.o
 mmc_core-$(CONFIG_DEBUG_FS)	+= debugfs.o
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index d5c176e..1be7055 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -40,6 +40,7 @@
 #include "bus.h"
 #include "host.h"
 #include "sdio_bus.h"
+#include "pwrseq.h"
 
 #include "mmc_ops.h"
 #include "sd_ops.h"
@@ -1615,6 +1616,8 @@ void mmc_power_up(struct mmc_host *host, u32 ocr)
 
 	mmc_host_clk_hold(host);
 
+	mmc_pwrseq_pre_power_on(host);
+
 	host->ios.vdd = fls(ocr) - 1;
 	host->ios.power_mode = MMC_POWER_UP;
 	/* Set initial state and call mmc_set_ios */
@@ -1645,6 +1648,8 @@ void mmc_power_up(struct mmc_host *host, u32 ocr)
 	 */
 	mmc_delay(10);
 
+	mmc_pwrseq_post_power_on(host);
+
 	mmc_host_clk_release(host);
 }
 
@@ -1655,6 +1660,8 @@ void mmc_power_off(struct mmc_host *host)
 
 	mmc_host_clk_hold(host);
 
+	mmc_pwrseq_power_off(host);
+
 	host->ios.clock = 0;
 	host->ios.vdd = 0;
 
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 0763644..8be0df7 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -30,6 +30,7 @@
 #include "core.h"
 #include "host.h"
 #include "slot-gpio.h"
+#include "pwrseq.h"
 
 #define cls_dev_to_mmc_host(d)	container_of(d, struct mmc_host, class_dev)
 
@@ -448,7 +449,7 @@ int mmc_of_parse(struct mmc_host *host)
 		host->dsr_req = 0;
 	}
 
-	return 0;
+	return mmc_pwrseq_alloc(host);
 }
 
 EXPORT_SYMBOL(mmc_of_parse);
@@ -588,6 +589,7 @@ EXPORT_SYMBOL(mmc_remove_host);
  */
 void mmc_free_host(struct mmc_host *host)
 {
+	mmc_pwrseq_free(host);
 	put_device(&host->class_dev);
 }
 
diff --git a/drivers/mmc/core/pwrseq.c b/drivers/mmc/core/pwrseq.c
new file mode 100644
index 0000000..bd08772
--- /dev/null
+++ b/drivers/mmc/core/pwrseq.c
@@ -0,0 +1,50 @@
+/*
+ *  Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ *
+ *  MMC power sequence management
+ */
+#include <linux/mmc/host.h>
+
+#include "pwrseq.h"
+
+
+int mmc_pwrseq_alloc(struct mmc_host *host)
+{
+	return 0;
+}
+
+void mmc_pwrseq_pre_power_on(struct mmc_host *host)
+{
+	struct mmc_pwrseq *pwrseq = host->pwrseq;
+
+	if (pwrseq && pwrseq->ops && pwrseq->ops->pre_power_on)
+		pwrseq->ops->pre_power_on(host);
+}
+
+void mmc_pwrseq_post_power_on(struct mmc_host *host)
+{
+	struct mmc_pwrseq *pwrseq = host->pwrseq;
+
+	if (pwrseq && pwrseq->ops && pwrseq->ops->post_power_on)
+		pwrseq->ops->post_power_on(host);
+}
+
+void mmc_pwrseq_power_off(struct mmc_host *host)
+{
+	struct mmc_pwrseq *pwrseq = host->pwrseq;
+
+	if (pwrseq && pwrseq->ops && pwrseq->ops->power_off)
+		pwrseq->ops->power_off(host);
+}
+
+void mmc_pwrseq_free(struct mmc_host *host)
+{
+	struct mmc_pwrseq *pwrseq = host->pwrseq;
+
+	if (pwrseq && pwrseq->ops && pwrseq->ops->free)
+		pwrseq->ops->free(host);
+}
diff --git a/drivers/mmc/core/pwrseq.h b/drivers/mmc/core/pwrseq.h
new file mode 100644
index 0000000..12aaf2b
--- /dev/null
+++ b/drivers/mmc/core/pwrseq.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+#ifndef _MMC_CORE_PWRSEQ_H
+#define _MMC_CORE_PWRSEQ_H
+
+struct mmc_pwrseq_ops {
+	void (*pre_power_on)(struct mmc_host *host);
+	void (*post_power_on)(struct mmc_host *host);
+	void (*power_off)(struct mmc_host *host);
+	void (*free)(struct mmc_host *host);
+};
+
+struct mmc_pwrseq {
+	struct mmc_pwrseq_ops *ops;
+};
+
+#ifdef CONFIG_OF
+
+int mmc_pwrseq_alloc(struct mmc_host *host);
+void mmc_pwrseq_pre_power_on(struct mmc_host *host);
+void mmc_pwrseq_post_power_on(struct mmc_host *host);
+void mmc_pwrseq_power_off(struct mmc_host *host);
+void mmc_pwrseq_free(struct mmc_host *host);
+
+#else
+
+static inline int mmc_pwrseq_alloc(struct mmc_host *host) { return 0; }
+static inline void mmc_pwrseq_pre_power_on(struct mmc_host *host) {}
+static inline void mmc_pwrseq_post_power_on(struct mmc_host *host) {}
+static inline void mmc_pwrseq_power_off(struct mmc_host *host) {}
+static inline void mmc_pwrseq_free(struct mmc_host *host) {}
+
+#endif
+
+#endif
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index b6bf718..0c8cbe5 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -195,6 +195,7 @@ struct mmc_context_info {
 };
 
 struct regulator;
+struct mmc_pwrseq;
 
 struct mmc_supply {
 	struct regulator *vmmc;		/* Card power supply */
@@ -206,6 +207,7 @@ struct mmc_host {
 	struct device		class_dev;
 	int			index;
 	const struct mmc_host_ops *ops;
+	struct mmc_pwrseq	*pwrseq;
 	unsigned int		f_min;
 	unsigned int		f_max;
 	unsigned int		f_init;
-- 
1.9.1

[PATCH V4 2/4] mmc: pwrseq: Document DT bindings for the simple MMC power sequence

[Ulf Hansson]

To support SOCs which specifies specific MMC power sequences, document
some MMC DT bindings to be able to describe these hardwares.

Let's also document bindings for a simple MMC power sequence provider,
which purpose is to support a set of common properties between various
SOCs.

In this initial step, let's also document a top level description of
the MMC power sequence and describe the compatible string used for the
simple MMC power sequence provider.

The simple MMC power sequence provider will initially support a reset
GPIO. From several earlier posted patches, it's clear that such
hardware exists. Especially some WLAN chips which are attached to an
SDIO interface may use a GPIO reset.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changed in v4:
	- None.

---
 .../devicetree/bindings/mmc/mmc-pwrseq-simple.txt    | 20 ++++++++++++++++++++
 Documentation/devicetree/bindings/mmc/mmc.txt        | 14 ++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt

diff --git a/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt
new file mode 100644
index 0000000..da333d9
--- /dev/null
+++ b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt
@@ -0,0 +1,20 @@
+* The simple MMC power sequence provider
+
+The purpose of the simple MMC power sequence provider is to supports a set of
+common properties between various SOC designs. It thus enables us to use the
+same provider for several SOC designs.
+
+Required properties:
+- compatible : contains "mmc-pwrseq-simple".
+
+Optional properties:
+- reset-gpios : contains a GPIO specifier. The reset GPIO is asserted at
+	initialization and prior we start the power up procedure of the card. It
+	will be de-asserted right after the power has been provided to the card.
+
+Example:
+
+	sdhci0_pwrseq {
+		compatible = "mmc-pwrseq-simple";
+		reset-gpios = <&gpio1 12 0>;
+	}
diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index bac1311..438899e 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -65,6 +65,18 @@ Optional SDIO properties:
 - enable-sdio-wakeup: Enables wake up of host system on SDIO IRQ assertion
 
 
+MMC power sequences:
+--------------------
+
+System on chip designs may specify a specific MMC power sequence. To
+successfully detect an (e)MMC/SD/SDIO card, that power sequence must be
+maintained while initializing the card.
+
+Optional property:
+- mmc-pwrseq: phandle to the MMC power sequence node. See "mmc-pwrseq-*"
+	for documentation of MMC power sequence bindings.
+
+
 Use of Function subnodes
 ------------------------
 
@@ -101,6 +113,7 @@ sdhci at ab000000 {
 	max-frequency = <50000000>;
 	keep-power-in-suspend;
 	enable-sdio-wakeup;
+	mmc-pwrseq = <&sdhci0_pwrseq>
 }
 
 Example with sdio function subnode:
@@ -114,6 +127,7 @@ mmc3: mmc at 01c12000 {
 	vmmc-supply = <&reg_vmmc3>;
 	bus-width = <4>;
 	non-removable;
+	mmc-pwrseq = <&sdhci0_pwrseq>
 	status = "okay";
 
 	brcmf: bcrmf at 1 {
-- 
1.9.1

[PATCH V4 3/4] mmc: pwrseq: Initial support for the simple MMC power sequence provider

[Ulf Hansson]

To add the core part for the MMC power sequence, let's start by adding
initial support for the simple MMC power sequence provider.

In this initial step, the MMC power sequence node are fetched and the
compatible string for the simple MMC power sequence provider are
verified.

At this point we don't parse the node for any properties, but instead
that will be handled from following patches. Since there are no
properties supported yet, let's just implement the ->alloc() and the
->free() callbacks.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changes in v4:
	- Fixed call to kfree().

---
 drivers/mmc/core/Makefile        |  2 +-
 drivers/mmc/core/pwrseq.c        | 61 +++++++++++++++++++++++++++++++++++++++-
 drivers/mmc/core/pwrseq.h        |  2 ++
 drivers/mmc/core/pwrseq_simple.c | 48 +++++++++++++++++++++++++++++++
 4 files changed, 111 insertions(+), 2 deletions(-)
 create mode 100644 drivers/mmc/core/pwrseq_simple.c

diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile
index ccdd35f..b39cbd2 100644
--- a/drivers/mmc/core/Makefile
+++ b/drivers/mmc/core/Makefile
@@ -8,5 +8,5 @@ mmc_core-y			:= core.o bus.o host.o \
 				   sdio.o sdio_ops.o sdio_bus.o \
 				   sdio_cis.o sdio_io.o sdio_irq.o \
 				   quirks.o slot-gpio.o
-mmc_core-$(CONFIG_OF)		+= pwrseq.o
+mmc_core-$(CONFIG_OF)		+= pwrseq.o pwrseq_simple.o
 mmc_core-$(CONFIG_DEBUG_FS)	+= debugfs.o
diff --git a/drivers/mmc/core/pwrseq.c b/drivers/mmc/core/pwrseq.c
index bd08772..2cea00e 100644
--- a/drivers/mmc/core/pwrseq.c
+++ b/drivers/mmc/core/pwrseq.c
@@ -7,14 +7,73 @@
  *
  *  MMC power sequence management
  */
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+
 #include <linux/mmc/host.h>
 
 #include "pwrseq.h"
 
+struct mmc_pwrseq_match {
+	const char *compatible;
+	int (*alloc)(struct mmc_host *host, struct device *dev);
+};
+
+static struct mmc_pwrseq_match pwrseq_match[] = {
+	{
+		.compatible = "mmc-pwrseq-simple",
+		.alloc = mmc_pwrseq_simple_alloc,
+	},
+};
+
+static struct mmc_pwrseq_match *mmc_pwrseq_find(struct device_node *np)
+{
+	struct mmc_pwrseq_match *match = ERR_PTR(-ENODEV);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(pwrseq_match); i++) {
+		if (of_device_is_compatible(np,	pwrseq_match[i].compatible)) {
+			match = &pwrseq_match[i];
+			break;
+		}
+	}
+
+	return match;
+}
 
 int mmc_pwrseq_alloc(struct mmc_host *host)
 {
-	return 0;
+	struct platform_device *pdev;
+	struct device_node *np;
+	struct mmc_pwrseq_match *match;
+	int ret = 0;
+
+	np = of_parse_phandle(host->parent->of_node, "mmc-pwrseq", 0);
+	if (!np)
+		return 0;
+
+	pdev = of_find_device_by_node(np);
+	if (!pdev) {
+		ret = -ENODEV;
+		goto err;
+	}
+
+	match = mmc_pwrseq_find(np);
+	if (IS_ERR(match)) {
+		ret = PTR_ERR(match);
+		goto err;
+	}
+
+	ret = match->alloc(host, &pdev->dev);
+	if (!ret)
+		dev_info(host->parent, "allocated mmc-pwrseq\n");
+
+err:
+	of_node_put(np);
+	return ret;
 }
 
 void mmc_pwrseq_pre_power_on(struct mmc_host *host)
diff --git a/drivers/mmc/core/pwrseq.h b/drivers/mmc/core/pwrseq.h
index 12aaf2b..bd860d8 100644
--- a/drivers/mmc/core/pwrseq.h
+++ b/drivers/mmc/core/pwrseq.h
@@ -27,6 +27,8 @@ void mmc_pwrseq_post_power_on(struct mmc_host *host);
 void mmc_pwrseq_power_off(struct mmc_host *host);
 void mmc_pwrseq_free(struct mmc_host *host);
 
+int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev);
+
 #else
 
 static inline int mmc_pwrseq_alloc(struct mmc_host *host) { return 0; }
diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
new file mode 100644
index 0000000..61c991e
--- /dev/null
+++ b/drivers/mmc/core/pwrseq_simple.c
@@ -0,0 +1,48 @@
+/*
+ *  Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ *
+ *  Simple MMC power sequence management
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/err.h>
+
+#include <linux/mmc/host.h>
+
+#include "pwrseq.h"
+
+struct mmc_pwrseq_simple {
+	struct mmc_pwrseq pwrseq;
+};
+
+static void mmc_pwrseq_simple_free(struct mmc_host *host)
+{
+	struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
+					struct mmc_pwrseq_simple, pwrseq);
+
+	kfree(pwrseq);
+	host->pwrseq = NULL;
+}
+
+static struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
+	.free = mmc_pwrseq_simple_free,
+};
+
+int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
+{
+	struct mmc_pwrseq_simple *pwrseq;
+
+	pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
+	if (!pwrseq)
+		return -ENOMEM;
+
+	pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
+	host->pwrseq = &pwrseq->pwrseq;
+
+	return 0;
+}
-- 
1.9.1

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Ulf Hansson]

The need for reset GPIOs has several times been pointed out from
erlier posted patchsets. Especially some WLAN chips which are
attached to an SDIO interface may use a GPIO reset.

The reset GPIO is asserted at initialization and prior we start the
power up procedure. The GPIO will be de-asserted right after the power
has been provided to the card, from the ->post_power_on() callback.

Note, the reset GPIO is optional. Thus we don't return an error even if
we can't find a GPIO for the consumer.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changes in v4:
	- Fixed call to kfree().

---
 drivers/mmc/core/pwrseq_simple.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
index 61c991e..0958c69 100644
--- a/drivers/mmc/core/pwrseq_simple.c
+++ b/drivers/mmc/core/pwrseq_simple.c
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/gpio/consumer.h>
 
 #include <linux/mmc/host.h>
 
@@ -18,31 +19,68 @@
 
 struct mmc_pwrseq_simple {
 	struct mmc_pwrseq pwrseq;
+	struct gpio_desc *reset_gpio;
 };
 
+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->reset_gpio))
+		gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
+}
+
+static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
+{
+	struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
+					struct mmc_pwrseq_simple, pwrseq);
+
+	if (!IS_ERR(pwrseq->reset_gpio))
+		gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
+}
+
 static void mmc_pwrseq_simple_free(struct mmc_host *host)
 {
 	struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
 					struct mmc_pwrseq_simple, pwrseq);
 
+	if (!IS_ERR(pwrseq->reset_gpio))
+		gpiod_put(pwrseq->reset_gpio);
+
 	kfree(pwrseq);
 	host->pwrseq = NULL;
 }
 
 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,
 	.free = mmc_pwrseq_simple_free,
 };
 
 int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
 {
 	struct mmc_pwrseq_simple *pwrseq;
+	int ret = 0;
 
 	pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
 	if (!pwrseq)
 		return -ENOMEM;
 
+	pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_HIGH);
+	if (IS_ERR(pwrseq->reset_gpio) &&
+		PTR_ERR(pwrseq->reset_gpio) != -ENOENT &&
+		PTR_ERR(pwrseq->reset_gpio) != -ENOSYS) {
+		ret = PTR_ERR(pwrseq->reset_gpio);
+		goto free;
+	}
+
 	pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
 	host->pwrseq = &pwrseq->pwrseq;
 
 	return 0;
+free:
+	kfree(pwrseq);
+	return ret;
 }
-- 
1.9.1

[PATCH V4 0/4] mmc: core: Add support for MMC power sequences

[Ulf Hansson]

On 19 January 2015 at 10:13, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> Changes in v4:
>         - Fixed call to kfree() in patch3 and patch4.
>
> Changes in v3:
>         Fixed comments from Mark Rutland:
>         - Document binding in one patch to get the big picture.
>         - Keep code and DT document consistent around how many GPIO resets we
>           support. I decided to go for one GPIO, we can extend that if needed
>           later on.
>         - Change compatible string for simple MMC power sequence and renamed the
>           file for its documentation.
>         - Updated commit messages according to above changes.
>
> Changes in v2:
>         Fixed comments from Russell King:
>         - Renamed pwrseq callbacks and corresponding interface functions.
>         - Move the call to the previous namned ->power_on() callback, to the
>           end of mmc_power_up() to get consistent behavior.
>
>
> This is yet another try to solve the issues of dealing with power sequences for
> the MMC subsystem. The latest attempt, see link below, took a generic approach
> by adding a new top level driver layer. That's was rejected by several reasons.
> http://lwn.net/Articles/602855/
>
> This time the approach is focused to fix the issues for MMC only.
>
> To give a short background, SOCs may specify a specific MMC power sequence. To
> successfully detect an (e)MMC/SD/SDIO card, that power sequence must be followed
> while initializing the card.
>
> To be able to handle these SOC specific power sequences, we add a MMC power
> sequence interface, which helps the mmc core to deal with such.
>
> A MMC power sequence provider then implements a set of callbacks from the above
> mentioned interface. The provider has a corresponding DT compatibility string
> and relies on CONFIG_OF to be set to find it's various resourses, like for
> example a GPIO reset.
>
> The mmc core will from mmc_of_parse() try find a "mmc-pwrseq" DT node and then
> call the corresponding MMC power sequence provider's initialization function.
>
>
> Ulf Hansson (4):
>   mmc: core: Initial support for MMC power sequences
>   mmc: pwrseq: Document DT bindings for the simple MMC power sequence
>   mmc: pwrseq: Initial support for the simple MMC power sequence
>     provider
>   mmc: pwrseq_simple: Add support for a reset GPIO pin
>
>  .../devicetree/bindings/mmc/mmc-pwrseq-simple.txt  |  20 ++++
>  Documentation/devicetree/bindings/mmc/mmc.txt      |  14 +++
>  drivers/mmc/core/Makefile                          |   2 +-
>  drivers/mmc/core/core.c                            |   7 ++
>  drivers/mmc/core/host.c                            |   4 +-
>  drivers/mmc/core/pwrseq.c                          | 109 +++++++++++++++++++++
>  drivers/mmc/core/pwrseq.h                          |  42 ++++++++
>  drivers/mmc/core/pwrseq_simple.c                   |  86 ++++++++++++++++
>  include/linux/mmc/host.h                           |   2 +
>  9 files changed, 284 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt
>  create mode 100644 drivers/mmc/core/pwrseq.c
>  create mode 100644 drivers/mmc/core/pwrseq.h
>  create mode 100644 drivers/mmc/core/pwrseq_simple.c
>
> --
> 1.9.1
>

To get some more testing of this code, I have now applied this v4 of
this patchset for my next branch.

Kind regards
Uffe

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Javier Martinez Canillas]

Hello Ulf,

On Mon, Jan 19, 2015 at 10:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>
>  int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>  {
>         struct mmc_pwrseq_simple *pwrseq;
> +       int ret = 0;
>
>         pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
>         if (!pwrseq)
>                 return -ENOMEM;
>
> +       pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_HIGH);

Any reason to not use the devm_gpiod_get_index() managed version instead?

AFAICT mmc_free_host() will free the device so in that case you won't
need to call gpiod_put() in mmc_pwrseq_simple_free().

This will also make easier to extend pwrseq_simple to support multiple
GPIOs like the DT binding implies.

Best regards,
Javier

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Ulf Hansson]

On 23 January 2015 at 16:56, Javier Martinez Canillas
<javier@dowhile0.org> wrote:
> Hello Ulf,
>
> On Mon, Jan 19, 2015 at 10:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>>
>>  int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>>  {
>>         struct mmc_pwrseq_simple *pwrseq;
>> +       int ret = 0;
>>
>>         pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
>>         if (!pwrseq)
>>                 return -ENOMEM;
>>
>> +       pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_HIGH);
>
> Any reason to not use the devm_gpiod_get_index() managed version instead?

This struct device don't have a bound driver to it. Thus this device
won't be freed automagically from the ->remove() or failed ->probe()
path.

>
> AFAICT mmc_free_host() will free the device so in that case you won't
> need to call gpiod_put() in mmc_pwrseq_simple_free().
>
> This will also make easier to extend pwrseq_simple to support multiple
> GPIOs like the DT binding implies.
>

Kind regards
Uffe

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Javier Martinez Canillas]

Hello Ulf,

On Fri, Jan 23, 2015 at 6:01 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>>
>> Any reason to not use the devm_gpiod_get_index() managed version instead?
>
> This struct device don't have a bound driver to it. Thus this device
> won't be freed automagically from the ->remove() or failed ->probe()
> path.
>

Right, I missed that. Thanks a lot for the clarification.

Best regards,
Javier

[PATCH V4 1/4] mmc: core: Initial support for MMC power sequences

[Javier Martinez Canillas]

Hello Ulf,

On Mon, Jan 19, 2015 at 10:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> System on chip designs may specify a specific MMC power sequence. To
> successfully detect an (e)MMC/SD/SDIO card, that power sequence must
> be followed while initializing the card.
>
> To be able to handle these SOC specific power sequences, let's add a
> MMC power sequence interface. It provides the following functions to
> help the mmc core to deal with these power sequences.
>
> mmc_pwrseq_alloc() - Invoked from mmc_of_parse(), to initialize data.
> mmc_pwrseq_pre_power_on()- Invoked in the beginning of mmc_power_up().
> mmc_pwrseq_post_power_on()- Invoked at the end in mmc_power_up().
> mmc_pwrseq_power_off()- Invoked from mmc_power_off().
> mmc_pwrseq_free() - Invoked from mmc_free_host(), to free data.
>
> Each MMC power sequence provider will be responsible to implement a set
> of callbacks. These callbacks mirrors the functions above.
>
> This patch adds the skeleton, following patches will extend the core of
> the MMC power sequence and add support for a specific simple MMC power
> sequence.
>
> Do note, since the mmc_pwrseq_alloc() is invoked from mmc_of_parse(),
> host drivers needs to make use of this API to enable the support for
> MMC power sequences. Moreover the MMC power sequence support depends on
> CONFIG_OF.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---

Patch looks good to me and I could successfully get the SDIO wlan chip
in the Snow Chromebook after extending the pwrseq_simple driver so on
Exynos5250 Snow Chromebook:

Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>

Best regards,
Javier

[PATCH V4 2/4] mmc: pwrseq: Document DT bindings for the simple MMC power sequence

[Javier Martinez Canillas]

Hello Ulf,

On Mon, Jan 19, 2015 at 10:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> To support SOCs which specifies specific MMC power sequences, document
> some MMC DT bindings to be able to describe these hardwares.
>
> Let's also document bindings for a simple MMC power sequence provider,
> which purpose is to support a set of common properties between various
> SOCs.
>
> In this initial step, let's also document a top level description of
> the MMC power sequence and describe the compatible string used for the
> simple MMC power sequence provider.
>
> The simple MMC power sequence provider will initially support a reset
> GPIO. From several earlier posted patches, it's clear that such
> hardware exists. Especially some WLAN chips which are attached to an
> SDIO interface may use a GPIO reset.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---

Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>

Best regards,
Javier

[PATCH V4 3/4] mmc: pwrseq: Initial support for the simple MMC power sequence provider

[Javier Martinez Canillas]

Hello Ulf,

On Mon, Jan 19, 2015 at 10:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> To add the core part for the MMC power sequence, let's start by adding
> initial support for the simple MMC power sequence provider.
>
> In this initial step, the MMC power sequence node are fetched and the
> compatible string for the simple MMC power sequence provider are
> verified.
>
> At this point we don't parse the node for any properties, but instead
> that will be handled from following patches. Since there are no
> properties supported yet, let's just implement the ->alloc() and the
> ->free() callbacks.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>

Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>

Best regards,
Javier

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Javier Martinez Canillas]

Hello Ulf,

On Mon, Jan 19, 2015 at 10:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> The need for reset GPIOs has several times been pointed out from
> erlier posted patchsets. Especially some WLAN chips which are
> attached to an SDIO interface may use a GPIO reset.
>
> The reset GPIO is asserted at initialization and prior we start the
> power up procedure. The GPIO will be de-asserted right after the power
> has been provided to the card, from the ->post_power_on() callback.
>
> Note, the reset GPIO is optional. Thus we don't return an error even if
> we can't find a GPIO for the consumer.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---

Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>

Best regards,
Javier

[PATCH V4 1/4] mmc: core: Initial support for MMC power sequences

[Ulf Hansson]

On 28 January 2015 at 11:17, Javier Martinez Canillas
<javier@dowhile0.org> wrote:
> Hello Ulf,
>
> On Mon, Jan 19, 2015 at 10:13 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>> System on chip designs may specify a specific MMC power sequence. To
>> successfully detect an (e)MMC/SD/SDIO card, that power sequence must
>> be followed while initializing the card.
>>
>> To be able to handle these SOC specific power sequences, let's add a
>> MMC power sequence interface. It provides the following functions to
>> help the mmc core to deal with these power sequences.
>>
>> mmc_pwrseq_alloc() - Invoked from mmc_of_parse(), to initialize data.
>> mmc_pwrseq_pre_power_on()- Invoked in the beginning of mmc_power_up().
>> mmc_pwrseq_post_power_on()- Invoked at the end in mmc_power_up().
>> mmc_pwrseq_power_off()- Invoked from mmc_power_off().
>> mmc_pwrseq_free() - Invoked from mmc_free_host(), to free data.
>>
>> Each MMC power sequence provider will be responsible to implement a set
>> of callbacks. These callbacks mirrors the functions above.
>>
>> This patch adds the skeleton, following patches will extend the core of
>> the MMC power sequence and add support for a specific simple MMC power
>> sequence.
>>
>> Do note, since the mmc_pwrseq_alloc() is invoked from mmc_of_parse(),
>> host drivers needs to make use of this API to enable the support for
>> MMC power sequences. Moreover the MMC power sequence support depends on
>> CONFIG_OF.
>>
>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>> ---
>
> Patch looks good to me and I could successfully get the SDIO wlan chip
> in the Snow Chromebook after extending the pwrseq_simple driver so on
> Exynos5250 Snow Chromebook:

By extending you mean?

>
> Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
> Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
>
> Best regards,
> Javier

Thanks for testing and reviewing! I have applied your tags to the patches.

Kind regards
Uffe

[PATCH V4 1/4] mmc: core: Initial support for MMC power sequences

[Javier Martinez Canillas]

Hello Ulf,

On Wed, Jan 28, 2015 at 12:36 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>>> ---
>>
>> Patch looks good to me and I could successfully get the SDIO wlan chip
>> in the Snow Chromebook after extending the pwrseq_simple driver so on
>> Exynos5250 Snow Chromebook:
>
> By extending you mean?
>

Sorry, I shoud had mentioned it. I meant the "Add multiple GPIO and
external clock to MMC pwrseq_simple" series [0] I posted before.

>>
>> Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
>> Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
>>
>> Best regards,
>> Javier
>
> Thanks for testing and reviewing! I have applied your tags to the patches.
>

You are welcome, thanks a lot for working on this.

Best regards,
Javier

[0]: http://www.spinics.net/lists/arm-kernel/msg395445.html

[PATCH V4 3/4] mmc: pwrseq: Initial support for the simple MMC power sequence provider

[Alexandre Courbot]

On Mon, Jan 19, 2015 at 6:13 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> To add the core part for the MMC power sequence, let's start by adding
> initial support for the simple MMC power sequence provider.
>
> In this initial step, the MMC power sequence node are fetched and the
> compatible string for the simple MMC power sequence provider are
> verified.
>
> At this point we don't parse the node for any properties, but instead
> that will be handled from following patches. Since there are no
> properties supported yet, let's just implement the ->alloc() and the
> ->free() callbacks.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>
> Changes in v4:
>         - Fixed call to kfree().
>
> ---
>  drivers/mmc/core/Makefile        |  2 +-
>  drivers/mmc/core/pwrseq.c        | 61 +++++++++++++++++++++++++++++++++++++++-
>  drivers/mmc/core/pwrseq.h        |  2 ++
>  drivers/mmc/core/pwrseq_simple.c | 48 +++++++++++++++++++++++++++++++
>  4 files changed, 111 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/mmc/core/pwrseq_simple.c
>
> diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile
> index ccdd35f..b39cbd2 100644
> --- a/drivers/mmc/core/Makefile
> +++ b/drivers/mmc/core/Makefile
> @@ -8,5 +8,5 @@ mmc_core-y                      := core.o bus.o host.o \
>                                    sdio.o sdio_ops.o sdio_bus.o \
>                                    sdio_cis.o sdio_io.o sdio_irq.o \
>                                    quirks.o slot-gpio.o
> -mmc_core-$(CONFIG_OF)          += pwrseq.o
> +mmc_core-$(CONFIG_OF)          += pwrseq.o pwrseq_simple.o
>  mmc_core-$(CONFIG_DEBUG_FS)    += debugfs.o
> diff --git a/drivers/mmc/core/pwrseq.c b/drivers/mmc/core/pwrseq.c
> index bd08772..2cea00e 100644
> --- a/drivers/mmc/core/pwrseq.c
> +++ b/drivers/mmc/core/pwrseq.c
> @@ -7,14 +7,73 @@
>   *
>   *  MMC power sequence management
>   */
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +
>  #include <linux/mmc/host.h>
>
>  #include "pwrseq.h"
>
> +struct mmc_pwrseq_match {
> +       const char *compatible;
> +       int (*alloc)(struct mmc_host *host, struct device *dev);
> +};
> +
> +static struct mmc_pwrseq_match pwrseq_match[] = {
> +       {
> +               .compatible = "mmc-pwrseq-simple",
> +               .alloc = mmc_pwrseq_simple_alloc,
> +       },
> +};
> +
> +static struct mmc_pwrseq_match *mmc_pwrseq_find(struct device_node *np)
> +{
> +       struct mmc_pwrseq_match *match = ERR_PTR(-ENODEV);
> +       int i;
> +
> +       for (i = 0; i < ARRAY_SIZE(pwrseq_match); i++) {
> +               if (of_device_is_compatible(np, pwrseq_match[i].compatible)) {
> +                       match = &pwrseq_match[i];
> +                       break;
> +               }
> +       }
> +
> +       return match;
> +}
>
>  int mmc_pwrseq_alloc(struct mmc_host *host)
>  {
> -       return 0;
> +       struct platform_device *pdev;
> +       struct device_node *np;
> +       struct mmc_pwrseq_match *match;
> +       int ret = 0;
> +
> +       np = of_parse_phandle(host->parent->of_node, "mmc-pwrseq", 0);
> +       if (!np)
> +               return 0;
> +
> +       pdev = of_find_device_by_node(np);
> +       if (!pdev) {
> +               ret = -ENODEV;
> +               goto err;
> +       }
> +
> +       match = mmc_pwrseq_find(np);
> +       if (IS_ERR(match)) {
> +               ret = PTR_ERR(match);
> +               goto err;
> +       }
> +
> +       ret = match->alloc(host, &pdev->dev);
> +       if (!ret)
> +               dev_info(host->parent, "allocated mmc-pwrseq\n");
> +
> +err:
> +       of_node_put(np);
> +       return ret;
>  }
>
>  void mmc_pwrseq_pre_power_on(struct mmc_host *host)
> diff --git a/drivers/mmc/core/pwrseq.h b/drivers/mmc/core/pwrseq.h
> index 12aaf2b..bd860d8 100644
> --- a/drivers/mmc/core/pwrseq.h
> +++ b/drivers/mmc/core/pwrseq.h
> @@ -27,6 +27,8 @@ void mmc_pwrseq_post_power_on(struct mmc_host *host);
>  void mmc_pwrseq_power_off(struct mmc_host *host);
>  void mmc_pwrseq_free(struct mmc_host *host);
>
> +int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev);
> +
>  #else
>
>  static inline int mmc_pwrseq_alloc(struct mmc_host *host) { return 0; }
> diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
> new file mode 100644
> index 0000000..61c991e
> --- /dev/null
> +++ b/drivers/mmc/core/pwrseq_simple.c
> @@ -0,0 +1,48 @@
> +/*
> + *  Copyright (C) 2014 Linaro Ltd
> + *
> + * Author: Ulf Hansson <ulf.hansson@linaro.org>
> + *
> + * License terms: GNU General Public License (GPL) version 2
> + *
> + *  Simple MMC power sequence management
> + */
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +
> +#include <linux/mmc/host.h>
> +
> +#include "pwrseq.h"
> +
> +struct mmc_pwrseq_simple {
> +       struct mmc_pwrseq pwrseq;
> +};
> +
> +static void mmc_pwrseq_simple_free(struct mmc_host *host)
> +{
> +       struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
> +                                       struct mmc_pwrseq_simple, pwrseq);
> +
> +       kfree(pwrseq);
> +       host->pwrseq = NULL;
> +}
> +
> +static struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
> +       .free = mmc_pwrseq_simple_free,
> +};
> +
> +int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
> +{
> +       struct mmc_pwrseq_simple *pwrseq;
> +
> +       pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
> +       if (!pwrseq)
> +               return -ENOMEM;
> +
> +       pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
> +       host->pwrseq = &pwrseq->pwrseq;

How about making this function return a struct mmc_pwrseq * so this
last line can be moved to mmc_pwrseq_alloc() instead of requiring all
power sequences to do it?

The same applies to

    host->pwrseq = NULL;

in mmc_pwrseq_simple_free(), which could be done in mmc_pwrseq_free() it seems.

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Alexandre Courbot]

On Mon, Jan 19, 2015 at 6:13 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> The need for reset GPIOs has several times been pointed out from
> erlier posted patchsets. Especially some WLAN chips which are
> attached to an SDIO interface may use a GPIO reset.
>
> The reset GPIO is asserted at initialization and prior we start the
> power up procedure. The GPIO will be de-asserted right after the power
> has been provided to the card, from the ->post_power_on() callback.
>
> Note, the reset GPIO is optional. Thus we don't return an error even if
> we can't find a GPIO for the consumer.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Excellent, with this I can probe the wifi chip on NVIDIA SHIELD which
requires a GPIO to be high for reset to be de-asserted.

The series:

Tested-by: Alexandre Courbot <acourbot@nvidia.com>

> ---
>
> Changes in v4:
>         - Fixed call to kfree().
>
> ---
>  drivers/mmc/core/pwrseq_simple.c | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
> index 61c991e..0958c69 100644
> --- a/drivers/mmc/core/pwrseq_simple.c
> +++ b/drivers/mmc/core/pwrseq_simple.c
> @@ -11,6 +11,7 @@
>  #include <linux/slab.h>
>  #include <linux/device.h>
>  #include <linux/err.h>
> +#include <linux/gpio/consumer.h>
>
>  #include <linux/mmc/host.h>
>
> @@ -18,31 +19,68 @@
>
>  struct mmc_pwrseq_simple {
>         struct mmc_pwrseq pwrseq;
> +       struct gpio_desc *reset_gpio;
>  };
>
> +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->reset_gpio))
> +               gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
> +}
> +
> +static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
> +{
> +       struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
> +                                       struct mmc_pwrseq_simple, pwrseq);
> +
> +       if (!IS_ERR(pwrseq->reset_gpio))
> +               gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
> +}
> +
>  static void mmc_pwrseq_simple_free(struct mmc_host *host)
>  {
>         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
>                                         struct mmc_pwrseq_simple, pwrseq);
>
> +       if (!IS_ERR(pwrseq->reset_gpio))
> +               gpiod_put(pwrseq->reset_gpio);
> +
>         kfree(pwrseq);
>         host->pwrseq = NULL;
>  }
>
>  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,
>         .free = mmc_pwrseq_simple_free,
>  };
>
>  int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>  {
>         struct mmc_pwrseq_simple *pwrseq;
> +       int ret = 0;
>
>         pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
>         if (!pwrseq)
>                 return -ENOMEM;
>
> +       pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_HIGH);

gpiod_get() will translate to exactly the same, with less characters.

Actually I see that the version in -next has support for multiple
GPIOs. You will probably want to look at Rojhalat's latest work on
GPIO arrays:

http://permalink.gmane.org/gmane.linux.kernel.gpio/6126

This code would be a great candidate to use this GPIO array API, but
since it is not in -next yet (should happen soon though) you might
want to consider doing it later.

Btw, I wasted a considerable amount of time on one of the defunct
previous attempts at power sequences, so I'm interested in reviewing
future versions of this patchset if you don't mind adding me to the CC
list. :)

[PATCH V4 3/4] mmc: pwrseq: Initial support for the simple MMC power sequence provider

[Ulf Hansson]

[...]

>> +int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>> +{
>> +       struct mmc_pwrseq_simple *pwrseq;
>> +
>> +       pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
>> +       if (!pwrseq)
>> +               return -ENOMEM;
>> +
>> +       pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
>> +       host->pwrseq = &pwrseq->pwrseq;
>
> How about making this function return a struct mmc_pwrseq * so this
> last line can be moved to mmc_pwrseq_alloc() instead of requiring all
> power sequences to do it?
>
> The same applies to
>
>     host->pwrseq = NULL;
>
> in mmc_pwrseq_simple_free(), which could be done in mmc_pwrseq_free() it seems.

Thanks for reviewing!

I like you suggestion, though $subject patch is already part of the PR for 3.20.

Feel free to send a patch, I would happily apply it.

Kind regards
Uffe

[PATCH V4 3/4] mmc: pwrseq: Initial support for the simple MMC power sequence provider

[Alexandre Courbot]

On Wed, Feb 11, 2015 at 1:28 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> [...]
>
>>> +int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>>> +{
>>> +       struct mmc_pwrseq_simple *pwrseq;
>>> +
>>> +       pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
>>> +       if (!pwrseq)
>>> +               return -ENOMEM;
>>> +
>>> +       pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
>>> +       host->pwrseq = &pwrseq->pwrseq;
>>
>> How about making this function return a struct mmc_pwrseq * so this
>> last line can be moved to mmc_pwrseq_alloc() instead of requiring all
>> power sequences to do it?
>>
>> The same applies to
>>
>>     host->pwrseq = NULL;
>>
>> in mmc_pwrseq_simple_free(), which could be done in mmc_pwrseq_free() it seems.
>
> Thanks for reviewing!
>
> I like you suggestion, though $subject patch is already part of the PR for 3.20.
>
> Feel free to send a patch, I would happily apply it.

Damn, why am I always so late to review patches...

I will send a fixup patch - better to have this done early.

Thanks!

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Ulf Hansson]

On 10 February 2015 at 10:12, Alexandre Courbot <gnurou@gmail.com> wrote:
> On Mon, Jan 19, 2015 at 6:13 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>> The need for reset GPIOs has several times been pointed out from
>> erlier posted patchsets. Especially some WLAN chips which are
>> attached to an SDIO interface may use a GPIO reset.
>>
>> The reset GPIO is asserted at initialization and prior we start the
>> power up procedure. The GPIO will be de-asserted right after the power
>> has been provided to the card, from the ->post_power_on() callback.
>>
>> Note, the reset GPIO is optional. Thus we don't return an error even if
>> we can't find a GPIO for the consumer.
>>
>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>
> Excellent, with this I can probe the wifi chip on NVIDIA SHIELD which
> requires a GPIO to be high for reset to be de-asserted.
>
> The series:
>
> Tested-by: Alexandre Courbot <acourbot@nvidia.com>

Thanks for testing! Unfortunate, I can't add you tag since this
patchset is already in the PR for 3.20.

>
>> ---
>>
>> Changes in v4:
>>         - Fixed call to kfree().
>>
>> ---
>>  drivers/mmc/core/pwrseq_simple.c | 38 ++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 38 insertions(+)
>>
>> diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
>> index 61c991e..0958c69 100644
>> --- a/drivers/mmc/core/pwrseq_simple.c
>> +++ b/drivers/mmc/core/pwrseq_simple.c
>> @@ -11,6 +11,7 @@
>>  #include <linux/slab.h>
>>  #include <linux/device.h>
>>  #include <linux/err.h>
>> +#include <linux/gpio/consumer.h>
>>
>>  #include <linux/mmc/host.h>
>>
>> @@ -18,31 +19,68 @@
>>
>>  struct mmc_pwrseq_simple {
>>         struct mmc_pwrseq pwrseq;
>> +       struct gpio_desc *reset_gpio;
>>  };
>>
>> +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->reset_gpio))
>> +               gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
>> +}
>> +
>> +static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
>> +{
>> +       struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
>> +                                       struct mmc_pwrseq_simple, pwrseq);
>> +
>> +       if (!IS_ERR(pwrseq->reset_gpio))
>> +               gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
>> +}
>> +
>>  static void mmc_pwrseq_simple_free(struct mmc_host *host)
>>  {
>>         struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
>>                                         struct mmc_pwrseq_simple, pwrseq);
>>
>> +       if (!IS_ERR(pwrseq->reset_gpio))
>> +               gpiod_put(pwrseq->reset_gpio);
>> +
>>         kfree(pwrseq);
>>         host->pwrseq = NULL;
>>  }
>>
>>  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,
>>         .free = mmc_pwrseq_simple_free,
>>  };
>>
>>  int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
>>  {
>>         struct mmc_pwrseq_simple *pwrseq;
>> +       int ret = 0;
>>
>>         pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
>>         if (!pwrseq)
>>                 return -ENOMEM;
>>
>> +       pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_HIGH);
>
> gpiod_get() will translate to exactly the same, with less characters.
>
> Actually I see that the version in -next has support for multiple
> GPIOs. You will probably want to look at Rojhalat's latest work on
> GPIO arrays:
>
> http://permalink.gmane.org/gmane.linux.kernel.gpio/6126

Cool!

>
> This code would be a great candidate to use this GPIO array API, but
> since it is not in -next yet (should happen soon though) you might
> want to consider doing it later.
>
> Btw, I wasted a considerable amount of time on one of the defunct
> previous attempts at power sequences, so I'm interested in reviewing
> future versions of this patchset if you don't mind adding me to the CC
> list. :)

:-)

I will keep you posted for future updates. Feel free to post patches
improving the mmc-pwrseq code yourself, I will happily review them.

Kind regards
Uffe

[PATCH V4 4/4] mmc: pwrseq_simple: Add support for a reset GPIO pin

[Linus Walleij]

On Wed, Feb 11, 2015 at 5:34 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On 10 February 2015 at 10:12, Alexandre Courbot <gnurou@gmail.com> wrote:

>> This code would be a great candidate to use this GPIO array API, but
>> since it is not in -next yet (should happen soon though) you might
>> want to consider doing it later.

This is now in my git and -next, I can take patches to pwrseq if Ulf
ACKs them to go through my GPIO tree.

Yours,
Linus Walleij