pwm: Add TI PWM subsystem driver

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@ti.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>

4 files changed, 190 insertions, 0 deletions

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6e556c7da81e..3dcb76d86a97 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -136,6 +136,7 @@ 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
@@ -146,6 +147,7 @@ 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
@@ -153,6 +155,15 @@ config  PWM_TIEHRPWM
           To compile this driver as a module, choose M here: the module
           will be called pwm-tiehrpwm.
 
+config  PWM_TIPWMSS
+        bool
+        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 3b3f4c9aa4ef..4fb39f8b6ba9 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -12,5 +12,6 @@ obj-$(CONFIG_PWM_SPEAR)		+= pwm-spear.o
 obj-$(CONFIG_PWM_TEGRA)         += pwm-tegra.o
 obj-$(CONFIG_PWM_TIECAP)        += pwm-tiecap.o
 obj-$(CONFIG_PWM_TIEHRPWM)      += pwm-tiehrpwm.o
+obj-$(CONFIG_PWM_TIPWMSS)       += pwm-tipwmss.o
 obj-$(CONFIG_PWM_TWL6030)       += pwm-twl6030.o
 obj-$(CONFIG_PWM_VT8500)        += pwm-vt8500.o
diff --git a/drivers/pwm/pwm-tipwmss.c b/drivers/pwm/pwm-tipwmss.c
new file mode 100644
index 000000000000..3448a1c88590
--- /dev/null
+++ b/drivers/pwm/pwm-tipwmss.c
@@ -0,0 +1,139 @@
+/*
+ * 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 "pwm-tipwmss.h"
+
+#define PWMSS_CLKCONFIG         0x8     /* Clock gating reg */
+#define PWMSS_CLKSTATUS         0xc     /* Clock gating status reg */
+
+struct pwmss_info {
+        void __iomem    *mmio_base;
+        struct mutex    pwmss_lock;
+        u16             pwmss_clkconfig;
+};
+
+u16 pwmss_submodule_state_change(struct device *dev, int set)
+{
+        struct pwmss_info *info = dev_get_drvdata(dev);
+        u16 val;
+
+        mutex_lock(&info->pwmss_lock);
+        val = readw(info->mmio_base + PWMSS_CLKCONFIG);
+        val |= set;
+        writew(val , info->mmio_base + PWMSS_CLKCONFIG);
+        mutex_unlock(&info->pwmss_lock);
+
+        return readw(info->mmio_base + PWMSS_CLKSTATUS);
+}
+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 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_err(&pdev->dev, "no child node found\n");
+
+        return ret;
+}
+
+static int 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)
+{
+        struct pwmss_info *info = dev_get_drvdata(dev);
+
+        info->pwmss_clkconfig = readw(info->mmio_base + PWMSS_CLKCONFIG);
+        pm_runtime_put_sync(dev);
+        return 0;
+}
+
+static int pwmss_resume(struct device *dev)
+{
+        struct pwmss_info *info = dev_get_drvdata(dev);
+
+        pm_runtime_get_sync(dev);
+        writew(info->pwmss_clkconfig, info->mmio_base + PWMSS_CLKCONFIG);
+        return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(pwmss_pm_ops, pwmss_suspend, pwmss_resume);
+
+static struct platform_driver pwmss_driver = {
+        .driver = {
+                .name   = "pwmss",
+                .owner  = THIS_MODULE,
+                .pm     = &pwmss_pm_ops,
+                .of_match_table = pwmss_of_match,
+        },
+        .probe  = pwmss_probe,
+        .remove = pwmss_remove,
+};
+
+module_platform_driver(pwmss_driver);
+
+MODULE_DESCRIPTION("PWM Subsystem driver");
+MODULE_AUTHOR("Texas Instruments");
+MODULE_LICENSE("GPL");
diff --git a/drivers/pwm/pwm-tipwmss.h b/drivers/pwm/pwm-tipwmss.h
new file mode 100644
index 000000000000..11f76a1e266b
--- /dev/null
+++ b/drivers/pwm/pwm-tipwmss.h
@@ -0,0 +1,39 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef __TIPWMSS_H
+#define __TIPWMSS_H
+
+#ifdef CONFIG_PWM_TIPWMSS
+/* PWM substem clock gating */
+#define PWMSS_ECAPCLK_EN        BIT(0)
+#define PWMSS_ECAPCLK_STOP_REQ  BIT(1)
+#define PWMSS_EPWMCLK_EN        BIT(8)
+#define PWMSS_EPWMCLK_STOP_REQ  BIT(9)
+
+#define PWMSS_ECAPCLK_EN_ACK    BIT(0)
+#define PWMSS_EPWMCLK_EN_ACK    BIT(8)
+
+extern u16 pwmss_submodule_state_change(struct device *dev, int set);
+#else
+static inline u16 pwmss_submodule_state_change(struct device *dev, int set)
+{
+        /* return success status value */
+        return 0xFFFF;
+}
+#endif
+#endif  /* __TIPWMSS_H */