[PATCH v4] PWM: PXA: add device tree support to PWM driver
Mike Dunn
mikedunn at newsguy.com
Wed Sep 18 11:59:42 EDT 2013
This patch adds device tree support to the PXA's PWM driver. Only an OF match
table is added; nothing needs to be extracted from the device tree node. The
existing ID table is reused for the match table data.
Tested on a Palm Treo 680 (both platform data and DT cases).
Signed-off-by: Mike Dunn <mikedunn at newsguy.com>
---
Thanks Stephen for the reviews and explanations.
Changle log:
v4:
- add second "compatible" string to pxa27x.dtsi
- change phrasing in binding doc pxa-pwm.txt to "one or more of"
v3:
- remove support for the polarity flag
- remove per-chip pwm index cell; define custom of_xlate()
(now #pwm-cells = <1>)
- "compatible" strings for all devices added to OF match table
- various stylistic changes recommended by reviewers
v2:
- of_match_table contains only the "pxa250-pwm" compatible string; require one
device instance per pwm
- add Documentation/devicetree/bindings/pwm/pxa-pwm.txt
- add support for polarity flag in DT and implement set_polarity() method
(the treo 680 inverts the signal between pwm out and backlight)
- return -EINVAL instead of -ENODEV if platform data or DT node not found
- output dev_info string if platform data missing
- expanded CC list of patch
Documentation/devicetree/bindings/pwm/pxa-pwm.txt | 31 ++++++++++++
arch/arm/boot/dts/pxa27x.dtsi | 24 +++++++++
drivers/pwm/pwm-pxa.c | 62 +++++++++++++++++++++++
3 files changed, 117 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pwm/pxa-pwm.txt
diff --git a/Documentation/devicetree/bindings/pwm/pxa-pwm.txt b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
new file mode 100644
index 0000000..01aca2e
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt
@@ -0,0 +1,31 @@
+Marvell PWM controller
+
+Required properties:
+- compatible: should be one or more of:
+ - "marvell,pxa250-pwm"
+ - "marvell,pxa270-pwm"
+ - "marvell,pxa168-pwm"
+ - "marvell,pxa910-pwm"
+- reg: physical base address and length of the registers used by the PWM channel
+ NB: One device instance must be created for each PWM that is used, so the
+ length covers only the register window for one PWM output, not that of the
+ entire PWM controller. Currently length is 0x10 for all supported devices.
+- #pwm-cells: should be 1. This cell is used to specify the period in
+ nanoseconds. (Because one device instance is created for each PWM output,
+ the per-chip index is superflous and not used.)
+
+Example PWM device node:
+
+pwm0: pwm at 40b00000 {
+ compatible = "marvell,pxa250-pwm";
+ reg = <0x40b00000 0x10>;
+ #pwm-cells = <1>;
+};
+
+Example PWM client node:
+
+backlight {
+ compatible = "pwm-backlight";
+ pwms = <&pwm0 5000000>;
+ ...
+}
diff --git a/arch/arm/boot/dts/pxa27x.dtsi b/arch/arm/boot/dts/pxa27x.dtsi
index d7c5d72..a705469 100644
--- a/arch/arm/boot/dts/pxa27x.dtsi
+++ b/arch/arm/boot/dts/pxa27x.dtsi
@@ -10,5 +10,29 @@
marvell,intc-priority;
marvell,intc-nr-irqs = <34>;
};
+
+ pwm0: pwm at 40b00000 {
+ compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
+ reg = <0x40b00000 0x10>;
+ #pwm-cells = <1>;
+ };
+
+ pwm1: pwm at 40b00010 {
+ compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
+ reg = <0x40b00010 0x10>;
+ #pwm-cells = <1>;
+ };
+
+ pwm2: pwm at 40c00000 {
+ compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
+ reg = <0x40c00000 0x10>;
+ #pwm-cells = <1>;
+ };
+
+ pwm3: pwm at 40c00010 {
+ compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
+ reg = <0x40c00010 0x10>;
+ #pwm-cells = <1>;
+ };
};
};
diff --git a/drivers/pwm/pwm-pxa.c b/drivers/pwm/pwm-pxa.c
index a4d2164..91b1cff 100644
--- a/drivers/pwm/pwm-pxa.c
+++ b/drivers/pwm/pwm-pxa.c
@@ -19,6 +19,7 @@
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>
+#include <linux/of_device.h>
#include <asm/div64.h>
@@ -124,6 +125,59 @@ static struct pwm_ops pxa_pwm_ops = {
.owner = THIS_MODULE,
};
+#ifdef CONFIG_OF
+/*
+ * Device tree users must create one device instance for each pwm channel.
+ * Hence we dispense with the HAS_SECONDARY_PWM and "tell" the original driver
+ * code that this is a single channel pxa25x-pwm. Currently all devices are
+ * supported identically.
+ */
+static struct of_device_id pwm_of_match[] = {
+ { .compatible = "marvell,pxa250-pwm", .data = &pwm_id_table[0]},
+ { .compatible = "marvell,pxa270-pwm", .data = &pwm_id_table[0]},
+ { .compatible = "marvell,pxa168-pwm", .data = &pwm_id_table[0]},
+ { .compatible = "marvell,pxa910-pwm", .data = &pwm_id_table[0]},
+ { }
+};
+MODULE_DEVICE_TABLE(of, pwm_of_match);
+
+static const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev)
+{
+ const struct of_device_id *id = of_match_device(pwm_of_match, dev);
+ if (id)
+ return (const struct platform_device_id *)id->data;
+ else
+ return NULL;
+}
+
+struct pwm_device *
+pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
+{
+ struct pwm_device *pwm;
+
+ pwm = pwm_request_from_chip(pc, 0, NULL);
+ if (IS_ERR(pwm))
+ return pwm;
+
+ pwm_set_period(pwm, args->args[0]);
+
+ return pwm;
+}
+
+#else /* !CONFIG_OF */
+static const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev)
+{
+ dev_err(dev, "missing platform data\n");
+ return NULL;
+}
+
+struct pwm_device *
+pxa_pwm_of_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
+{
+ return NULL;
+}
+#endif
+
static int pwm_probe(struct platform_device *pdev)
{
const struct platform_device_id *id = platform_get_device_id(pdev);
@@ -131,6 +185,11 @@ static int pwm_probe(struct platform_device *pdev)
struct resource *r;
int ret = 0;
+ if (id == NULL) /* using device tree */
+ id = pxa_pwm_get_id_dt(&pdev->dev);
+ if (id == NULL)
+ return -EINVAL;
+
pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
if (pwm == NULL) {
dev_err(&pdev->dev, "failed to allocate memory\n");
@@ -145,6 +204,8 @@ static int pwm_probe(struct platform_device *pdev)
pwm->chip.ops = &pxa_pwm_ops;
pwm->chip.base = -1;
pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
+ pwm->chip.of_xlate = pxa_pwm_of_xlate;
+ pwm->chip.of_pwm_n_cells = 1;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r);
@@ -176,6 +237,7 @@ static struct platform_driver pwm_driver = {
.driver = {
.name = "pxa25x-pwm",
.owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(pwm_of_match),
},
.probe = pwm_probe,
.remove = pwm_remove,
--
1.8.1.5
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