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Date: Sat, 27 Oct 2012 14:49:57 +1300
From: Tony Prisk <linux@...sktech.co.nz>
To: thierry.reding@...onic-design.de
Cc: arm@...nel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Tony Prisk <linux@...sktech.co.nz>
Subject: [PATCH v5] pwm: vt8500: Update vt8500 PWM driver support
This patch updates pwm-vt8500.c to support devicetree probing and
make use of the common clock subsystem.
A binding document describing the PWM controller found on
arch-vt8500 is also included.
Signed-off-by: Tony Prisk <linux@...sktech.co.nz>
---
v4:
return err from clk_enable rather than -EBUSY
v5:
replace IS_ERR_OR_NULL with IS_ERR as pointed out by Chris Brand
.../devicetree/bindings/pwm/vt8500-pwm.txt | 17 ++++
drivers/pwm/pwm-vt8500.c | 86 ++++++++++++++------
2 files changed, 80 insertions(+), 23 deletions(-)
create mode 100644 Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
diff --git a/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt b/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
new file mode 100644
index 0000000..bcc6367
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
@@ -0,0 +1,17 @@
+VIA/Wondermedia VT8500/WM8xxx series SoC PWM controller
+
+Required properties:
+- compatible: should be "via,vt8500-pwm"
+- reg: physical base address and length of the controller's registers
+- #pwm-cells: should be 2. The first cell specifies the per-chip index
+ of the PWM to use and the second cell is the period in nanoseconds.
+- clocks: phandle to the PWM source clock
+
+Example:
+
+pwm1: pwm@...20000 {
+ #pwm-cells = <2>;
+ compatible = "via,vt8500-pwm";
+ reg = <0xd8220000 0x1000>;
+ clocks = <&clkpwm>;
+};
diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index ad14389..970b0c6 100644
--- a/drivers/pwm/pwm-vt8500.c
+++ b/drivers/pwm/pwm-vt8500.c
@@ -1,7 +1,8 @@
/*
* drivers/pwm/pwm-vt8500.c
*
- * Copyright (C) 2010 Alexey Charkov <alchark@...il.com>
+ * Copyright (C) 2012 Tony Prisk <linux@...sktech.co.nz>
+ * Copyright (C) 2010 Alexey Charkov <alchark@...il.com>
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
@@ -21,14 +22,24 @@
#include <linux/io.h>
#include <linux/pwm.h>
#include <linux/delay.h>
+#include <linux/clk.h>
#include <asm/div64.h>
-#define VT8500_NR_PWMS 4
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+
+/*
+ * SoC architecture allocates register space for 4 PWMs but only
+ * 2 are currently implemented.
+ */
+#define VT8500_NR_PWMS 2
struct vt8500_chip {
struct pwm_chip chip;
void __iomem *base;
+ struct clk *clk;
};
#define to_vt8500_chip(chip) container_of(chip, struct vt8500_chip, chip)
@@ -52,7 +63,7 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
unsigned long long c;
unsigned long period_cycles, prescale, pv, dc;
- c = 25000000/2; /* wild guess --- need to implement clocks */
+ c = clk_get_rate(vt8500->clk);
c = c * period_ns;
do_div(c, 1000000000);
period_cycles = c;
@@ -85,8 +96,15 @@ static int vt8500_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
static int vt8500_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
+ int err;
struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
+ err = clk_enable(vt8500->clk);
+ if (err < 0)
+ dev_err(chip->dev, "failed to enable clock\n");
+ return err;
+ };
+
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
writel(5, vt8500->base + (pwm->hwpwm << 4));
return 0;
@@ -98,6 +116,8 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
pwm_busy_wait(vt8500->base + 0x40 + pwm->hwpwm, (1 << 0));
writel(0, vt8500->base + (pwm->hwpwm << 4));
+
+ clk_disable(vt8500->clk);
}
static struct pwm_ops vt8500_pwm_ops = {
@@ -107,12 +127,24 @@ static struct pwm_ops vt8500_pwm_ops = {
.owner = THIS_MODULE,
};
-static int __devinit pwm_probe(struct platform_device *pdev)
+static const struct of_device_id vt8500_pwm_dt_ids[] = {
+ { .compatible = "via,vt8500-pwm", },
+ { /* Sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, vt8500_pwm_dt_ids);
+
+static int vt8500_pwm_probe(struct platform_device *pdev)
{
struct vt8500_chip *chip;
struct resource *r;
+ struct device_node *np = pdev->dev.of_node;
int ret;
+ if (!np) {
+ dev_err(&pdev->dev, "invalid devicetree node\n");
+ return -EINVAL;
+ }
+
chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
if (chip == NULL) {
dev_err(&pdev->dev, "failed to allocate memory\n");
@@ -124,6 +156,12 @@ static int __devinit pwm_probe(struct platform_device *pdev)
chip->chip.base = -1;
chip->chip.npwm = VT8500_NR_PWMS;
+ chip->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(chip->clk)) {
+ dev_err(&pdev->dev, "clock source not specified\n");
+ return PTR_ERR(chip->clk);
+ }
+
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (r == NULL) {
dev_err(&pdev->dev, "no memory resource defined\n");
@@ -131,18 +169,26 @@ static int __devinit pwm_probe(struct platform_device *pdev)
}
chip->base = devm_request_and_ioremap(&pdev->dev, r);
- if (chip->base == NULL)
+ if (!chip->base)
return -EADDRNOTAVAIL;
+ ret = clk_prepare(chip->clk);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to prepare clock\n");
+ return ret;
+ }
+
ret = pwmchip_add(&chip->chip);
- if (ret < 0)
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to add PWM chip\n");
return ret;
+ }
platform_set_drvdata(pdev, chip);
return ret;
}
-static int __devexit pwm_remove(struct platform_device *pdev)
+static int vt8500_pwm_remove(struct platform_device *pdev)
{
struct vt8500_chip *chip;
@@ -150,28 +196,22 @@ static int __devexit pwm_remove(struct platform_device *pdev)
if (chip == NULL)
return -ENODEV;
+ clk_unprepare(chip->clk);
+
return pwmchip_remove(&chip->chip);
}
-static struct platform_driver pwm_driver = {
+static struct platform_driver vt8500_pwm_driver = {
+ .probe = vt8500_pwm_probe,
+ .remove = vt8500_pwm_remove,
.driver = {
.name = "vt8500-pwm",
.owner = THIS_MODULE,
+ .of_match_table = vt8500_pwm_dt_ids,
},
- .probe = pwm_probe,
- .remove = __devexit_p(pwm_remove),
};
+module_platform_driver(vt8500_pwm_driver);
-static int __init pwm_init(void)
-{
- return platform_driver_register(&pwm_driver);
-}
-arch_initcall(pwm_init);
-
-static void __exit pwm_exit(void)
-{
- platform_driver_unregister(&pwm_driver);
-}
-module_exit(pwm_exit);
-
-MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("VT8500 PWM Driver");
+MODULE_AUTHOR("Tony Prisk <linux@...sktech.co.nz>");
+MODULE_LICENSE("GPL v2");
--
1.7.9.5
--
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