[PATCH 1/8] PWMSS: Add PWM Subsystem driver for parent<->child relationship

[Philip, Avinash]

In some platforms (like am33xx), PWM sub modules (ECAP, EHRPWM, EQEP)
are integrated to PWM subsystem. These PWM submodules has resources
shared and only one register bit-field is provided to control
module/clock enable/disable, makes it difficult to handle common
resources from independent PWMSS submodule drivers.

So the solution here implemented in this patch is, to create driver for
PWMSS and take the role of parent driver for PWM submodules. PWMSS
parent driver enumerates all the child nodes under PWMSS module. Also
symbol "pwmss_submodule_state_change" exported to enable clock gating
for individual PWMSS submodules, and submodule drivers has to enable
clock gating from their drivers.

As this is only supported during DT boot, the parent<->child relationship
is created and populated in DT execution flow. The only required change
is inside DTS file, making EHRPWM & ECAP as a child to PWMSS node.

Signed-off-by: Philip, Avinash <avinashphilip@xxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
Cc: Rob Landley <rob@xxxxxxxxxxx>
---
:000000 100644 0000000... b6c2814... A	Documentation/devicetree/bindings/pwm/tipwmss.txt
:100644 100644 ed81720... 99ebcfa... M	drivers/pwm/Kconfig
:100644 100644 acfe482... 1001bdb... M	drivers/pwm/Makefile
:000000 100644 0000000... d30a802... A	drivers/pwm/tipwmss.c
:000000 100644 0000000... 83fdc29... A	drivers/pwm/tipwmss.h
 Documentation/devicetree/bindings/pwm/tipwmss.txt |   30 +++++
 drivers/pwm/Kconfig                               |   11 ++
 drivers/pwm/Makefile                              |    1 +
 drivers/pwm/tipwmss.c                             |  136 +++++++++++++++++++++
 drivers/pwm/tipwmss.h                             |    8 ++
 5 files changed, 186 insertions(+), 0 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/tipwmss.txt b/Documentation/devicetree/bindings/pwm/tipwmss.txt
new file mode 100644
index 0000000..b6c2814
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/tipwmss.txt
@@ -0,0 +1,30 @@
+TI SOC based PWM Subsystem
+
+Required properties:
+- compatible: Must be "ti,am33xx-pwmss";
+- reg: physical base address and size of the registers map. For am33xx,
+	4 set of register maps present, PWMSS config space, ECAP register space,
+	EQEP register space, EHRPWM register space.
+- address-cells: Specify the number of u32 entries needed in child nodes.
+		 Should set to 1.
+- size-cells: specify inumber of u32 entries needed to specify child nodes size
+		in reg property. Should set to 1.
+- ranges: describes the address mapping of a memory-mapped bus. Should set to empty
+	  as parent and child address space is identical.
+
+Also child nodes should also populated under PWMSS DT node.
+Example:
+pwmss0: pwmss@48300000 {
+	compatible = "ti,am33xx-pwmss";
+	reg = <0x48300000 0x10
+		0x48300100 0x80
+		0x48300180 0x80
+		0x48300200 0x80>;
+	ti,hwmods = "epwmss0";
+	#address-cells = <1>;
+	#size-cells = <1>;
+	status = "disabled";
+	ranges;
+
+	/* child nodes go here */
+};
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index ed81720..99ebcfa 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -125,6 +125,7 @@ config PWM_TEGRA
 config  PWM_TIECAP
 	tristate "ECAP PWM support"
 	depends on SOC_AM33XX
+	select PWM_TIPWMSS
 	help
 	  PWM driver support for the ECAP APWM controller found on AM33XX
 	  TI SOC
@@ -135,6 +136,7 @@ config  PWM_TIECAP
 config  PWM_TIEHRPWM
 	tristate "EHRPWM PWM support"
 	depends on SOC_AM33XX
+	select PWM_TIPWMSS
 	help
 	  PWM driver support for the EHRPWM controller found on AM33XX
 	  TI SOC
@@ -142,6 +144,15 @@ config  PWM_TIEHRPWM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-tiehrpwm.
 
+config  PWM_TIPWMSS
+	tristate "TI PWM Subsytem parent support"
+	depends on SOC_AM33XX && (PWM_TIEHRPWM || PWM_TIECAP)
+	help
+	  PWM Subsystem driver support for AM33xx SOC.
+
+	  PWM submodules require PWM config space access from submodule
+	  drivers and require common parent driver support.
+
 config PWM_TWL6030
 	tristate "TWL6030 PWM support"
 	depends on TWL4030_CORE
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index acfe482..1001bdb 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -11,5 +11,6 @@ obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
 obj-$(CONFIG_PWM_TEGRA)		+= pwm-tegra.o
 obj-$(CONFIG_PWM_TIECAP)	+= pwm-tiecap.o
 obj-$(CONFIG_PWM_TIEHRPWM)	+= pwm-tiehrpwm.o
+obj-$(CONFIG_PWM_TIPWMSS)	+= tipwmss.o
 obj-$(CONFIG_PWM_TWL6030)	+= pwm-twl6030.o
 obj-$(CONFIG_PWM_VT8500)	+= pwm-vt8500.o
diff --git a/drivers/pwm/tipwmss.c b/drivers/pwm/tipwmss.c
new file mode 100644
index 0000000..d30a802
--- /dev/null
+++ b/drivers/pwm/tipwmss.c
@@ -0,0 +1,136 @@
+/*
+ * TI PWM Subsystem driver
+ *
+ * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+#include <linux/of_device.h>
+
+#include "tipwmss.h"
+
+struct pwmss_info {
+	void __iomem	*mmio_base;
+	struct mutex	pwmss_lock;
+};
+
+#define PWMSS_CLKCONFIG		8
+
+void pwmss_submodule_state_change(struct device *dev, int pos, bool enable)
+{
+	struct pwmss_info *info = dev_get_drvdata(dev);
+	u16 val;
+
+	val = readw(info->mmio_base + PWMSS_CLKCONFIG);
+	if (enable)
+		val |= 1 << pos;
+	else
+		val &= ~(1 << pos);
+	mutex_lock(&info->pwmss_lock);
+	writew(val , info->mmio_base + PWMSS_CLKCONFIG);
+	mutex_unlock(&info->pwmss_lock);
+}
+EXPORT_SYMBOL(pwmss_submodule_state_change);
+
+static const struct of_device_id pwmss_of_match[] = {
+	{
+		.compatible	= "ti,am33xx-pwmss",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, pwmss_of_match);
+
+static int __devinit pwmss_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct resource *r;
+	struct pwmss_info *info;
+	struct device_node *node = pdev->dev.of_node;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
+	if (!info) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	mutex_init(&info->pwmss_lock);
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r) {
+		dev_err(&pdev->dev, "no memory resource defined\n");
+		return -ENODEV;
+	}
+
+	info->mmio_base = devm_request_and_ioremap(&pdev->dev, r);
+	if (!info->mmio_base)
+		return -EADDRNOTAVAIL;
+
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_get_sync(&pdev->dev);
+	platform_set_drvdata(pdev, info);
+
+	/* Populate all the child nodes here... */
+	ret = of_platform_populate(node, NULL, NULL, &pdev->dev);
+	if (ret)
+		dev_warn(&pdev->dev, "Doesn't have any child node\n");
+
+	return ret;
+}
+
+static int __devexit pwmss_remove(struct platform_device *pdev)
+{
+	struct pwmss_info *info = platform_get_drvdata(pdev);
+
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	mutex_destroy(&info->pwmss_lock);
+	return 0;
+}
+
+static int pwmss_suspend(struct device *dev)
+{
+	pm_runtime_put_sync(dev);
+	return 0;
+}
+
+static int pwmss_resume(struct device *dev)
+{
+	pm_runtime_get_sync(dev);
+	return 0;
+}
+
+static const struct dev_pm_ops pwmss_pm_ops = {
+	.suspend	= pwmss_suspend,
+	.resume		= pwmss_resume,
+};
+
+static struct platform_driver pwmss_driver = {
+	.driver	= {
+		.name	= "pwmss",
+		.owner	= THIS_MODULE,
+		.pm	= &pwmss_pm_ops,
+		.of_match_table	= of_match_ptr(pwmss_of_match),
+	},
+	.probe	= pwmss_probe,
+	.remove	= __devexit_p(pwmss_remove),
+};
+
+module_platform_driver(pwmss_driver);
+
+MODULE_DESCRIPTION("pwmss driver");
+MODULE_AUTHOR("Texas Instruments");
+MODULE_LICENSE("GPL");
diff --git a/drivers/pwm/tipwmss.h b/drivers/pwm/tipwmss.h
new file mode 100644
index 0000000..83fdc29
--- /dev/null
+++ b/drivers/pwm/tipwmss.h
@@ -0,0 +1,8 @@
+#ifdef CONFIG_PWM_TIPWMSS
+extern void pwmss_submodule_state_change(struct device *dev, int pos,
+		bool enable);
+#else
+static inline void pwmss_submodule_state_change(struct device *dev, int pos,
+		bool enable)
+{}
+#endif
-- 
1.7.0.4

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