[v8,11/11] pwm: Add Raspberry Pi Firmware based PWM bus

Message ID 20210312122454.24480-12-nsaenzjulienne@suse.de
State New
Headers show
Series
  • Raspberry Pi PoE HAT fan support
Related show

Commit Message

Nicolas Saenz Julienne March 12, 2021, 12:24 p.m.
Adds support to control the PWM bus available in official Raspberry Pi
PoE HAT. Only RPi's co-processor has access to it, so commands have to
be sent through RPi's firmware mailbox interface.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

---

Changes since v7:
 - Remove unwarranted RPI_PWM_DEF_DUTY_REG usage

 Changes since v6:
- Use %pe
- Round divisions properly
- Use dev_err_probe()
- Pass check_patch

Changes since v3:
 - Rename compatible string to be more explicit WRT to bus's limitations

Changes since v2:
 - Use devm_rpi_firmware_get()
 - Rename driver
 - Small cleanups

Changes since v1:
 - Use default pwm bindings and get rid of xlate() function
 - Correct spelling errors
 - Correct apply() function
 - Round values
 - Fix divisions in arm32 mode
 - Small cleanups

 drivers/pwm/Kconfig               |   9 ++
 drivers/pwm/Makefile              |   1 +
 drivers/pwm/pwm-raspberrypi-poe.c | 206 ++++++++++++++++++++++++++++++
 3 files changed, 216 insertions(+)
 create mode 100644 drivers/pwm/pwm-raspberrypi-poe.c

Comments

Nicolas Saenz Julienne March 15, 2021, 4:12 p.m. | #1
Hi Uwe,

On Fri, 2021-03-12 at 21:12 +0100, Uwe Kleine-König wrote:
> Hello Nicolas,
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> 
> 2021?

Yes.

> > + * For more information on Raspberry Pi's PoE hat see:
> > + * https://www.raspberrypi.org/products/poe-hat/
> 
> Out of personal interest: Is this hat also able to power a RPi CM4?

I haven't tested it, and can't at the moment (no PoE injector available). But
the physical pin layout, and routing in CM4's IO board fits the hat. So I'd say
yes.

> > + * Limitations:
> > + *  - No disable bit, so a disabled PWM is simulated by duty_cycle 0
> > + *  - Only normal polarity
> > + *  - Fixed 12.5 kHz period
> > + *
> > + * The current period is completed when HW is reconfigured.
> > + */
> 
> Other than that as mentioned in the previous round: This looks good,
> 
> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thanks!

> What is your thought about how to get this series merged?
> At least input, staging, armsoc, clk, reset anf firmware are touched. Do you
> prepare a branch for merging in the relevant trees (once you have all the
> necessary Acks)?

As per Linusw suggestion I'll send a pull request myself into the SoC tree and
hope for the best. :)

Regards,
Nicolas
Thierry Reding March 22, 2021, 11:56 a.m. | #2
On Fri, Mar 12, 2021 at 01:24:54PM +0100, Nicolas Saenz Julienne wrote:
> Adds support to control the PWM bus available in official Raspberry Pi
> PoE HAT. Only RPi's co-processor has access to it, so commands have to
> be sent through RPi's firmware mailbox interface.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> 
> ---
> 
> Changes since v7:
>  - Remove unwarranted RPI_PWM_DEF_DUTY_REG usage
> 
>  Changes since v6:
> - Use %pe
> - Round divisions properly
> - Use dev_err_probe()
> - Pass check_patch
> 
> Changes since v3:
>  - Rename compatible string to be more explicit WRT to bus's limitations
> 
> Changes since v2:
>  - Use devm_rpi_firmware_get()
>  - Rename driver
>  - Small cleanups
> 
> Changes since v1:
>  - Use default pwm bindings and get rid of xlate() function
>  - Correct spelling errors
>  - Correct apply() function
>  - Round values
>  - Fix divisions in arm32 mode
>  - Small cleanups
> 
>  drivers/pwm/Kconfig               |   9 ++
>  drivers/pwm/Makefile              |   1 +
>  drivers/pwm/pwm-raspberrypi-poe.c | 206 ++++++++++++++++++++++++++++++
>  3 files changed, 216 insertions(+)
>  create mode 100644 drivers/pwm/pwm-raspberrypi-poe.c

Acked-by: Thierry Reding <thierry.reding@gmail.com>

Patch

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index a7a7a9f26aef..d3371ac7b871 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -431,6 +431,15 @@  config PWM_PXA
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-pxa.
 
+config PWM_RASPBERRYPI_POE
+	tristate "Raspberry Pi Firwmware PoE Hat PWM support"
+	# Make sure not 'y' when RASPBERRYPI_FIRMWARE is 'm'. This can only
+	# happen when COMPILE_TEST=y, hence the added !RASPBERRYPI_FIRMWARE.
+	depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
+	help
+	  Enable Raspberry Pi firmware controller PWM bus used to control the
+	  official RPI PoE hat
+
 config PWM_RCAR
 	tristate "Renesas R-Car PWM support"
 	depends on ARCH_RENESAS || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 4e35a55fa7b6..d3879619bd76 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -39,6 +39,7 @@  obj-$(CONFIG_PWM_NTXEC)		+= pwm-ntxec.o
 obj-$(CONFIG_PWM_OMAP_DMTIMER)	+= pwm-omap-dmtimer.o
 obj-$(CONFIG_PWM_PCA9685)	+= pwm-pca9685.o
 obj-$(CONFIG_PWM_PXA)		+= pwm-pxa.o
+obj-$(CONFIG_PWM_RASPBERRYPI_POE)	+= pwm-raspberrypi-poe.o
 obj-$(CONFIG_PWM_RCAR)		+= pwm-rcar.o
 obj-$(CONFIG_PWM_RENESAS_TPU)	+= pwm-renesas-tpu.o
 obj-$(CONFIG_PWM_ROCKCHIP)	+= pwm-rockchip.o
diff --git a/drivers/pwm/pwm-raspberrypi-poe.c b/drivers/pwm/pwm-raspberrypi-poe.c
new file mode 100644
index 000000000000..71ade5e55069
--- /dev/null
+++ b/drivers/pwm/pwm-raspberrypi-poe.c
@@ -0,0 +1,206 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ * For more information on Raspberry Pi's PoE hat see:
+ * https://www.raspberrypi.org/products/poe-hat/
+ *
+ * Limitations:
+ *  - No disable bit, so a disabled PWM is simulated by duty_cycle 0
+ *  - Only normal polarity
+ *  - Fixed 12.5 kHz period
+ *
+ * The current period is completed when HW is reconfigured.
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+
+#include <soc/bcm2835/raspberrypi-firmware.h>
+#include <dt-bindings/pwm/raspberrypi,firmware-poe-pwm.h>
+
+#define RPI_PWM_MAX_DUTY		255
+#define RPI_PWM_PERIOD_NS		80000 /* 12.5 kHz */
+
+#define RPI_PWM_CUR_DUTY_REG		0x0
+
+struct raspberrypi_pwm {
+	struct rpi_firmware *firmware;
+	struct pwm_chip chip;
+	unsigned int duty_cycle;
+};
+
+struct raspberrypi_pwm_prop {
+	__le32 reg;
+	__le32 val;
+	__le32 ret;
+} __packed;
+
+static inline
+struct raspberrypi_pwm *raspberrypi_pwm_from_chip(struct pwm_chip *chip)
+{
+	return container_of(chip, struct raspberrypi_pwm, chip);
+}
+
+static int raspberrypi_pwm_set_property(struct rpi_firmware *firmware,
+					u32 reg, u32 val)
+{
+	struct raspberrypi_pwm_prop msg = {
+		.reg = cpu_to_le32(reg),
+		.val = cpu_to_le32(val),
+	};
+	int ret;
+
+	ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL,
+				    &msg, sizeof(msg));
+	if (ret)
+		return ret;
+	if (msg.ret)
+		return -EIO;
+
+	return 0;
+}
+
+static int raspberrypi_pwm_get_property(struct rpi_firmware *firmware,
+					u32 reg, u32 *val)
+{
+	struct raspberrypi_pwm_prop msg = {
+		.reg = reg
+	};
+	int ret;
+
+	ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL,
+				    &msg, sizeof(msg));
+	if (ret)
+		return ret;
+	if (msg.ret)
+		return -EIO;
+
+	*val = le32_to_cpu(msg.val);
+
+	return 0;
+}
+
+static void raspberrypi_pwm_get_state(struct pwm_chip *chip,
+				      struct pwm_device *pwm,
+				      struct pwm_state *state)
+{
+	struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip);
+
+	state->period = RPI_PWM_PERIOD_NS;
+	state->duty_cycle = DIV_ROUND_UP(rpipwm->duty_cycle * RPI_PWM_PERIOD_NS,
+					 RPI_PWM_MAX_DUTY);
+	state->enabled = !!(rpipwm->duty_cycle);
+	state->polarity = PWM_POLARITY_NORMAL;
+}
+
+static int raspberrypi_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+				 const struct pwm_state *state)
+{
+	struct raspberrypi_pwm *rpipwm = raspberrypi_pwm_from_chip(chip);
+	unsigned int duty_cycle;
+	int ret;
+
+	if (state->period < RPI_PWM_PERIOD_NS ||
+	    state->polarity != PWM_POLARITY_NORMAL)
+		return -EINVAL;
+
+	if (!state->enabled)
+		duty_cycle = 0;
+	else if (state->duty_cycle < RPI_PWM_PERIOD_NS)
+		duty_cycle = DIV_ROUND_DOWN_ULL(state->duty_cycle * RPI_PWM_MAX_DUTY,
+						RPI_PWM_PERIOD_NS);
+	else
+		duty_cycle = RPI_PWM_MAX_DUTY;
+
+	if (duty_cycle == rpipwm->duty_cycle)
+		return 0;
+
+	ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,
+					   duty_cycle);
+	if (ret) {
+		dev_err(chip->dev, "Failed to set duty cycle: %pe\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
+	rpipwm->duty_cycle = duty_cycle;
+
+	return 0;
+}
+
+static const struct pwm_ops raspberrypi_pwm_ops = {
+	.get_state = raspberrypi_pwm_get_state,
+	.apply = raspberrypi_pwm_apply,
+	.owner = THIS_MODULE,
+};
+
+static int raspberrypi_pwm_probe(struct platform_device *pdev)
+{
+	struct device_node *firmware_node;
+	struct device *dev = &pdev->dev;
+	struct rpi_firmware *firmware;
+	struct raspberrypi_pwm *rpipwm;
+	int ret;
+
+	firmware_node = of_get_parent(dev->of_node);
+	if (!firmware_node) {
+		dev_err(dev, "Missing firmware node\n");
+		return -ENOENT;
+	}
+
+	firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);
+	of_node_put(firmware_node);
+	if (!firmware)
+		return dev_err_probe(dev, -EPROBE_DEFER,
+				     "Failed to get firmware handle\n");
+
+	rpipwm = devm_kzalloc(&pdev->dev, sizeof(*rpipwm), GFP_KERNEL);
+	if (!rpipwm)
+		return -ENOMEM;
+
+	rpipwm->firmware = firmware;
+	rpipwm->chip.dev = dev;
+	rpipwm->chip.ops = &raspberrypi_pwm_ops;
+	rpipwm->chip.base = -1;
+	rpipwm->chip.npwm = RASPBERRYPI_FIRMWARE_PWM_NUM;
+
+	platform_set_drvdata(pdev, rpipwm);
+
+	ret = raspberrypi_pwm_get_property(rpipwm->firmware, RPI_PWM_CUR_DUTY_REG,
+					   &rpipwm->duty_cycle);
+	if (ret) {
+		dev_err(dev, "Failed to get duty cycle: %pe\n", ERR_PTR(ret));
+		return ret;
+	}
+
+	return pwmchip_add(&rpipwm->chip);
+}
+
+static int raspberrypi_pwm_remove(struct platform_device *pdev)
+{
+	struct raspberrypi_pwm *rpipwm = platform_get_drvdata(pdev);
+
+	return pwmchip_remove(&rpipwm->chip);
+}
+
+static const struct of_device_id raspberrypi_pwm_of_match[] = {
+	{ .compatible = "raspberrypi,firmware-poe-pwm", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match);
+
+static struct platform_driver raspberrypi_pwm_driver = {
+	.driver = {
+		.name = "raspberrypi-poe-pwm",
+		.of_match_table = raspberrypi_pwm_of_match,
+	},
+	.probe = raspberrypi_pwm_probe,
+	.remove = raspberrypi_pwm_remove,
+};
+module_platform_driver(raspberrypi_pwm_driver);
+
+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
+MODULE_DESCRIPTION("Raspberry Pi Firmware Based PWM Bus Driver");
+MODULE_LICENSE("GPL v2");