The pwrseq subsystem handles complex power sequences, typically useful
for subsystems that makes use of discoverable buses, like for example
MMC and I2C.
The pwrseq subsystem is dependant on CONFIG_OF to be able to parse a DT
childnode to find out what power sequence method to bind for a device.
>From the DT childnode, the pwrseq DT parser tries to locate a
"power-method" property, which string is matched towards the list of
supported pwrseq methods.
Each pwrseq method implements it's own power sequence and interfaces
the pwrseq core through a few callback functions.
To instantiate a pwrseq method, clients shall use the devm_pwrseq_get()
API. If needed, clients can explicity drop the references to a pwrseq
method using devm_pwrseq_put() API.
Besides instantiation, the pwrseq API provides clients opportunity to
select a certain power state. In this intial version, PWRSEQ_POWER_ON
and PWRSEQ_POWER_OFF are supported. Those are also mandatory for each
pwrseq method to support.
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
.../devicetree/bindings/pwrseq/pwrseq.txt | 48 ++++++
drivers/Makefile | 2 +-
drivers/pwrseq/Makefile | 2 +
drivers/pwrseq/core.c | 175 ++++++++++++++++++++
drivers/pwrseq/core.h | 37 +++++
drivers/pwrseq/method.c | 38 +++++
include/linux/pwrseq.h | 50 ++++++
7 files changed, 351 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/pwrseq/pwrseq.txt
create mode 100644 drivers/pwrseq/Makefile
create mode 100644 drivers/pwrseq/core.c
create mode 100644 drivers/pwrseq/core.h
create mode 100644 drivers/pwrseq/method.c
create mode 100644 include/linux/pwrseq.h
diff --git a/Documentation/devicetree/bindings/pwrseq/pwrseq.txt b/Documentation/devicetree/bindings/pwrseq/pwrseq.txt
new file mode 100644
index 0000000..80848ae
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwrseq/pwrseq.txt
@@ -0,0 +1,48 @@
+Power sequence DT bindings
+
+Each power sequence method has a corresponding "power-method" property string.
+This property shall be set in a subnode for a device. That subnode should also
+describe resourses which are specific to that power method.
+
+Do note, power sequences as such isn't encoded through DT. Instead those are
+implemented by each power method.
+
+Required subnode properties:
+- power-method: should contain the string for the power method to bind.
+
+ Supported power methods: None.
+
+Example:
+
+Note, the "clock" power method in this example isn't actually supported, but
+used to visualize how a childnode could be described.
+
+// WLAN SDIO channel
+sdi1_per2@80118000 {
+ compatible = "arm,pl18x", "arm,primecell";
+ reg = <0x80118000 0x1000>;
+ interrupts = <0 50 IRQ_TYPE_LEVEL_HIGH>;
+
+ dmas = <&dma 32 0 0x2>, /* Logical - DevToMem */
+ <&dma 32 0 0x0>; /* Logical - MemToDev */
+ dma-names = "rx", "tx";
+
+ clocks = <&prcc_kclk 2 4>, <&prcc_pclk 2 6>;
+ clock-names = "sdi", "apb_pclk";
+
+ arm,primecell-periphid = <0x10480180>;
+ max-frequency = <100000000>;
+ bus-width = <4>;
+ non-removable;
+ pinctrl-names = "default", "sleep";
+ pinctrl-0 = <&sdi1_default_mode>;
+ pinctrl-1 = <&sdi1_sleep_mode>;
+
+ status = "okay";
+
+ pwrseq: pwrseq1 {
+ power-method = "clock";
+ clocks = <&someclk 1 2>, <&someclk 3 4>;
+ clock-names = "pwrseq1", "pwrseq2";
+ };
+};
diff --git a/drivers/Makefile b/drivers/Makefile
index f98b50d..ac1bf5b 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -128,7 +128,7 @@ endif
obj-$(CONFIG_DCA) += dca/
obj-$(CONFIG_HID) += hid/
obj-$(CONFIG_PPC_PS3) += ps3/
-obj-$(CONFIG_OF) += of/
+obj-$(CONFIG_OF) += of/ pwrseq/
obj-$(CONFIG_SSB) += ssb/
obj-$(CONFIG_BCMA) += bcma/
obj-$(CONFIG_VHOST_RING) += vhost/
diff --git a/drivers/pwrseq/Makefile b/drivers/pwrseq/Makefile
new file mode 100644
index 0000000..afb914f
--- /dev/null
+++ b/drivers/pwrseq/Makefile
@@ -0,0 +1,2 @@
+#Support for the power sequence subsystem
+obj-y = core.o method.o
diff --git a/drivers/pwrseq/core.c b/drivers/pwrseq/core.c
new file mode 100644
index 0000000..baf7bb6
--- /dev/null
+++ b/drivers/pwrseq/core.c
@@ -0,0 +1,175 @@
+/*
+ * Core of the power sequence subsystem
+ *
+ * Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/device.h>
+#include <linux/string.h>
+#include <linux/err.h>
+#include <linux/of.h>
+
+#include <linux/pwrseq.h>
+#include "core.h"
+
+static int pwrseq_find(const char *power_method)
+{
+ int i;
+
+ for (i = 0; pwrseq_methods[i].bind_method != NULL; i++)
+ if (!strcasecmp(power_method, pwrseq_methods[i].method))
+ return i;
+ return -ENODEV;
+}
+
+static void devm_pwrseq_release(struct device *dev, void *res)
+{
+ struct pwrseq *ps = res;
+
+ dev_dbg(dev, "%s: Release method=%s\n", __func__, ps->method);
+
+ ps->ps_ops->release(ps);
+ of_node_put(ps->np_child);
+}
+
+static struct pwrseq *pwrseq_get(struct device *dev,
+ struct device_node *np,
+ const char *power_method)
+{
+ struct pwrseq *ps;
+ int ret;
+
+ ret = pwrseq_find(power_method);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ ps = devres_alloc(devm_pwrseq_release, sizeof(ps), GFP_KERNEL);
+ if (!ps)
+ return ERR_PTR(-ENOMEM);
+
+ ps->dev = dev;
+ ps->np_child = np;
+ ps->method = pwrseq_methods[ret].method;
+
+ /*
+ * The on/off states is mandatory to be supported. Additional states
+ * shall be added by each method during binding.
+ */
+ ps->supported_states = PWRSEQ_POWER_OFF | PWRSEQ_POWER_ON;
+ /*
+ * The default current state is PWRSEQ_POWER_OFF, it may be updated
+ * during binding.
+ */
+ ps->current_state = PWRSEQ_POWER_OFF;
+
+ ret = pwrseq_methods[ret].bind_method(ps);
+ if (ret) {
+ devres_free(ps);
+ return ERR_PTR(ret);
+ }
+
+ devres_add(dev, ps);
+ return ps;
+}
+
+static int pwrseq_of_find(struct device *dev,
+ struct device_node **np_child,
+ const char **power_method)
+{
+ struct device_node *np;
+ const char *pm;
+
+ if (!dev->of_node)
+ return -ENODEV;
+
+ /* Parse childnodes to find a power-method property. */
+ for_each_child_of_node(dev->of_node, np) {
+ if (!of_property_read_string(np, "power-method", &pm)) {
+ *np_child = np;
+ *power_method = pm;
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+static struct pwrseq *_devm_pwrseq_get(struct device *dev, bool optional)
+{
+ struct pwrseq *ps;
+ struct device_node *np;
+ const char *pm;
+ int ret;
+
+ if (!dev)
+ return ERR_PTR(-ENODEV);
+
+ ret = pwrseq_of_find(dev, &np, &pm);
+ if (ret < 0) {
+ return ERR_PTR(ret);
+ } else if (ret) {
+ ps = pwrseq_get(dev, np, pm);
+ if (IS_ERR(ps))
+ of_node_put(np);
+ } else if (optional) {
+ ps = pwrseq_get(dev, NULL, "dummy");
+ } else {
+ return ERR_PTR(-ENODEV);
+ }
+
+ if (!IS_ERR(ps))
+ dev_dbg(dev, "%s: Bound method=%s\n", __func__, ps->method);
+
+ return ps;
+}
+
+struct pwrseq *devm_pwrseq_get_optional(struct device *dev)
+{
+ return _devm_pwrseq_get(dev, true);
+}
+EXPORT_SYMBOL_GPL(devm_pwrseq_get_optional);
+
+struct pwrseq *devm_pwrseq_get(struct device *dev)
+{
+ return _devm_pwrseq_get(dev, false);
+}
+EXPORT_SYMBOL_GPL(devm_pwrseq_get);
+
+static int devm_pwrseq_match(struct device *dev, void *res, void *data)
+{
+ struct pwrseq **ps = res;
+
+ return *ps == data;
+}
+
+void devm_pwrseq_put(struct pwrseq *ps)
+{
+ devres_release(ps->dev, devm_pwrseq_release, devm_pwrseq_match, ps);
+}
+EXPORT_SYMBOL_GPL(devm_pwrseq_put);
+
+int pwrseq_select_state(struct pwrseq *ps, enum pwrseq_state ps_state)
+{
+ int ret = 0;
+
+ if (ps->current_state != ps_state)
+ ret = ps->ps_ops->select_state(ps, ps_state);
+
+ if (!ret)
+ ps->current_state = ps_state;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_select_state);
+
+unsigned int pwrseq_supported_states(struct pwrseq *ps)
+{
+ return ps->supported_states;
+}
+EXPORT_SYMBOL_GPL(pwrseq_supported_states);
diff --git a/drivers/pwrseq/core.h b/drivers/pwrseq/core.h
new file mode 100644
index 0000000..84a6449
--- /dev/null
+++ b/drivers/pwrseq/core.h
@@ -0,0 +1,37 @@
+/*
+ * Core private header for the power sequence subsystem
+ *
+ * Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#ifndef __PWRSEQ_PWRSEQ_H
+#define __PWRSEQ_PWRSEQ_H
+
+#include <linux/pwrseq.h>
+
+struct pwrseq_ops {
+ int (*select_state)(struct pwrseq *, enum pwrseq_state);
+ void (*release)(struct pwrseq *);
+};
+
+struct pwrseq {
+ struct device *dev;
+ struct device_node *np_child;
+ const char *method;
+ enum pwrseq_state supported_states;
+ enum pwrseq_state current_state;
+ struct pwrseq_ops *ps_ops;
+ void *data;
+};
+
+struct pwrseq_method {
+ int (*bind_method)(struct pwrseq *);
+ const char *method;
+};
+
+extern struct pwrseq_method pwrseq_methods[];
+#endif
diff --git a/drivers/pwrseq/method.c b/drivers/pwrseq/method.c
new file mode 100644
index 0000000..fe16579
--- /dev/null
+++ b/drivers/pwrseq/method.c
@@ -0,0 +1,38 @@
+/*
+ * Implements a dummy power method for power sequence subsystem
+ *
+ * Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#include <linux/kernel.h>
+
+#include <linux/pwrseq.h>
+#include "core.h"
+
+static int pwrseq_dummy_select_state(struct pwrseq *ps, enum pwrseq_state s)
+{
+ return 0;
+}
+
+static void pwrseq_dummy_release(struct pwrseq *ps) { }
+
+static struct pwrseq_ops pwrseq_dummy_ops = {
+ .select_state = pwrseq_dummy_select_state,
+ .release = pwrseq_dummy_release,
+};
+
+static int pwrseq_dummy_bind(struct pwrseq *ps)
+{
+ ps->ps_ops = &pwrseq_dummy_ops;
+ return 0;
+}
+
+/* The extern list of supported power sequence_methods */
+struct pwrseq_method pwrseq_methods[] = {
+ { pwrseq_dummy_bind, "dummy" },
+ { NULL, NULL },
+};
diff --git a/include/linux/pwrseq.h b/include/linux/pwrseq.h
new file mode 100644
index 0000000..528b544
--- /dev/null
+++ b/include/linux/pwrseq.h
@@ -0,0 +1,50 @@
+/*
+ * Interface for the power sequence subsystem
+ *
+ * Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+#ifndef __LINUX_PWRSEQ_PWRSEQ_H
+#define __LINUX_PWRSEQ_PWRSEQ_H
+
+#include <linux/bitops.h>
+
+struct device;
+struct pwrseq;
+
+enum pwrseq_state {
+ PWRSEQ_POWER_OFF = BIT(0),
+ PWRSEQ_POWER_ON = BIT(1),
+};
+
+#ifdef CONFIG_OF
+extern struct pwrseq *devm_pwrseq_get(struct device *dev);
+extern struct pwrseq *devm_pwrseq_get_optional(struct device *dev);
+extern void devm_pwrseq_put(struct pwrseq *ps);
+extern int pwrseq_select_state(struct pwrseq *ps, unsigned int ps_state);
+extern unsigned int pwrseq_supported_states(struct pwrseq *ps);
+#else
+static inline struct pwrseq *devm_pwrseq_get(struct device *dev)
+{
+ return ERR_PTR(-ENODEV);
+}
+static inline struct pwrseq *devm_pwrseq_get_optional(struct device *dev)
+{
+ return ERR_PTR(-ENODEV);
+}
+static inline void devm_pwrseq_put(struct pwrseq *ps) {}
+static inline int pwrseq_select_state(struct pwrseq *ps,
+ enum pwrseq_state ps_state)
+{
+ return 0;
+}
+static inline unsigned int pwrseq_supported_states(struct pwrseq *ps)
+{
+ return 0;
+}
+#endif
+
+#endif /* __LINUX_PWRSEQ_PWRSEQ_H */
--
1.7.9.5
--
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