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 platform_device id table is reused for the match table data. Support for inverted polarity is also added. Tested on a Palm Treo 680 (both platform data and DT cases). Signed-off-by: Mike Dunn <mikedunn@xxxxxxxxxxx> --- Changle log: Resent with expanded Cc list 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 | 33 +++++++++++++ arch/arm/boot/dts/pxa27x.dtsi | 24 ++++++++++ drivers/pwm/pwm-pxa.c | 57 +++++++++++++++++++++++ 3 files changed, 114 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..7b09bfa --- /dev/null +++ b/Documentation/devicetree/bindings/pwm/pxa-pwm.txt @@ -0,0 +1,33 @@ +Marvell pwm controller + +Required properties: +- compatible: + for pxa25x, pxa27x, pxa168, pxa910: must be compatible = "marvell,pxa250-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 3. + cell 1: the per-chip index of the PWM to use, + cell 2: the period in nanoseconds, + cell 3: flags; set bit 0 to specify inverse polarity. The pwm controller + does not implement reverse polarity, but some boards may pass the pwm output + through an external inverter, which can cause problems if a client device + assumes that an increase in the duty cycle results in an increase in output + power. The pwm-backlight is an example of such a client. + +Example pwm device node: + +pwm0: pwm@40b00000 { + compatible = "marvell,pxa250-pwm"; + reg = <0x40b00000 0x10>; + #pwm-cells = <3>; +}; + +Example pwm client node: + +backlight { + compatible = "pwm-backlight"; + pwms = <&pwm0 0 5000000 1>; /* pwm output is inverted */ + ... +} diff --git a/arch/arm/boot/dts/pxa27x.dtsi b/arch/arm/boot/dts/pxa27x.dtsi index d7c5d72..a12fe8e 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@40b00000 { + compatible = "marvell,pxa250-pwm"; + reg = <0x40b00000 0x10>; + #pwm-cells = <3>; + }; + + pwm1: pwm@40b00010 { + compatible = "marvell,pxa250-pwm"; + reg = <0x40b00010 0x10>; + #pwm-cells = <3>; + }; + + pwm2: pwm@40c00000 { + compatible = "marvell,pxa250-pwm"; + reg = <0x40c00000 0x10>; + #pwm-cells = <3>; + }; + + pwm3: pwm@40c00010 { + compatible = "marvell,pxa250-pwm"; + reg = <0x40c00010 0x10>; + #pwm-cells = <3>; + }; }; }; diff --git a/drivers/pwm/pwm-pxa.c b/drivers/pwm/pwm-pxa.c index a4d2164..33e6a7d 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> @@ -48,6 +49,7 @@ struct pxa_pwm_chip { struct clk *clk; void __iomem *mmio_base; + enum pwm_polarity polarity; }; static inline struct pxa_pwm_chip *to_pxa_pwm_chip(struct pwm_chip *chip) @@ -88,6 +90,15 @@ static int pxa_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm, else dc = (pv + 1) * duty_ns / period_ns; + if (pc->polarity == PWM_POLARITY_INVERSED) { + if (dc & PWMDCR_FD) + dc = 0; /* continuously low */ + else if (dc == 0) + dc = PWMDCR_FD; /* continuously high */ + else + dc = 1023 - dc; /* complement duty cycle */ + } + /* NOTE: the clock to PWM has to be enabled first * before writing to the registers */ @@ -117,13 +128,51 @@ static void pxa_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) clk_disable_unprepare(pc->clk); } +static int pxa_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, + enum pwm_polarity polarity) +{ + struct pxa_pwm_chip *pc = to_pxa_pwm_chip(chip); + pc->polarity = polarity; + return 0; +} + static struct pwm_ops pxa_pwm_ops = { .config = pxa_pwm_config, .enable = pxa_pwm_enable, .disable = pxa_pwm_disable, + .set_polarity = pxa_pwm_set_polarity, .owner = THIS_MODULE, }; +#ifdef CONFIG_OF +/* + * Device tree users should 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. + */ +static struct of_device_id pwm_of_match[] = { + { .compatible = "marvell,pxa250-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 *pwm_pxa_devid = + of_match_device(pwm_of_match, dev); + if (pwm_pxa_devid) + return (const struct platform_device_id *)pwm_pxa_devid->data; + else + return NULL; +} +#else /* !CONFIG_OF */ +static const struct platform_device_id *pxa_pwm_get_id_dt(struct device *dev) +{ + dev_info(dev, "missing platform data\n"); + return NULL; +} +#endif + static int pwm_probe(struct platform_device *pdev) { const struct platform_device_id *id = platform_get_device_id(pdev); @@ -131,6 +180,11 @@ 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 +199,8 @@ 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 = of_pwm_xlate_with_flags; + pwm->chip.of_pwm_n_cells = 3; r = platform_get_resource(pdev, IORESOURCE_MEM, 0); pwm->mmio_base = devm_ioremap_resource(&pdev->dev, r); @@ -176,6 +232,7 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html