The aim of this series is to add support to the fan found on RPi's PoE
HAT. Some commentary on the design can be found below. But the imporant
part to the people CC'd here not involved with PWM is that, in order to
achieve this properly, we also have to fix the firmware interface the
driver uses to communicate with the PWM bus (and many other low level
functions). Specifically, we have to make sure the firmware interface
isn't unbound while consumers are still up. So, patch #1 introduces
reference counting in the firwmware interface driver and patches #2 to
#7 update all firmware users. Patches #8 to #10 introduce the new PWM
driver.
I sent everything as a single series as the final version of the PWM
drivers depends on the firwmare fixes, but I'll be happy to split this
into two separate series if you think it's better.
--- Original cover letter below ---
This series aims at adding support to RPi's official PoE HAT fan[1].
The HW setup is the following:
| Raspberry Pi | PoE HAT |
arm core -> Mailbox -> RPi co-processor -> I2C -> Atmel MCU -> PWM -> FAN
The arm cores have only access to the mailbox interface, as i2c0, even if
physically accessible, is to be used solely by the co-processor
(VideoCore 4/6).
This series implements a PWM bus, and has pwm-fan sitting on top of it as per
this discussion: https://lkml.org/lkml/2018/9/2/486. Although this design has a
series of shortcomings:
- It depends on a DT binding: it's not flexible if a new hat shows up with new
functionality, we're not 100% sure we'll be able to expand it without
breaking backwards compatibility. But without it we can't make use of DT
thermal-zones, which IMO is overkill.
- We're using pwm-fan, writing a hwmon driver would, again, give us more
flexibility, but it's not really needed at the moment.
I personally think that it's not worth the effort, it's unlikely we'll get
things right in advance. And ultimately, if the RPi people come up with
something new, we can always write a new driver/bindings from scratch (as in
not reusing previous code).
That said, I'm more than happy to change things if there is a consensus that
another design will do the trick.
[1] https://www.raspberrypi.org/blog/introducing-power-over-ethernet-poe-hat/
---
Changes since v2:
- Introduce devm_rpi_firmware_get()
- Small cleanups in PWM driver
Changes since v1:
- Address PWM driver changes
- Fix binding, now with 2 cells
- Add reference count to rpi_firmware_get()
Nicolas Saenz Julienne (11):
firmware: raspberrypi: Introduce devm_rpi_firmware_get()
clk: bcm: rpi: Release firmware handle on unbind
gpio: raspberrypi-exp: Release firmware handle on unbind
reset: raspberrypi: Release firmware handle on unbind
soc: bcm: raspberrypi-power: Release firmware handle on unbind
staging: vchiq: Release firmware handle on unbind
input: raspberrypi-ts: Release firmware handle when not needed
firmware: raspberrypi: Get rid of rpi_firmware_get()
dt-bindings: pwm: Add binding for RPi firmware PWM bus
DO NOT MERGE: ARM: dts: Add RPi's official PoE hat support
pwm: Add Raspberry Pi Firmware based PWM bus
.../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 20 ++
arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 54 +++++
drivers/clk/bcm/clk-raspberrypi.c | 2 +-
drivers/firmware/raspberrypi.c | 37 ++-
drivers/gpio/gpio-raspberrypi-exp.c | 2 +-
drivers/input/touchscreen/raspberrypi-ts.c | 2 +-
drivers/pwm/Kconfig | 9 +
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-raspberrypi-poe.c | 216 ++++++++++++++++++
drivers/reset/reset-raspberrypi.c | 2 +-
drivers/soc/bcm/raspberrypi-power.c | 2 +-
.../interface/vchiq_arm/vchiq_arm.c | 2 +-
.../pwm/raspberrypi,firmware-pwm.h | 13 ++
include/soc/bcm2835/raspberrypi-firmware.h | 6 +-
14 files changed, 356 insertions(+), 12 deletions(-)
create mode 100644 drivers/pwm/pwm-raspberrypi-poe.c
create mode 100644 include/dt-bindings/pwm/raspberrypi,firmware-pwm.h
--
2.29.1
Use devm_rpi_firmware_get() so as to make sure we release RPi's firmware
interface when unbinding the device.
Signed-off-by: Nicolas Saenz Julienne <[email protected]>
---
Changes since v2:
- Use devm_rpi_firmware_get(), instead of remove function
drivers/soc/bcm/raspberrypi-power.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/soc/bcm/raspberrypi-power.c b/drivers/soc/bcm/raspberrypi-power.c
index 5d1aacdd84ef..068715d6e66d 100644
--- a/drivers/soc/bcm/raspberrypi-power.c
+++ b/drivers/soc/bcm/raspberrypi-power.c
@@ -177,7 +177,7 @@ static int rpi_power_probe(struct platform_device *pdev)
return -ENODEV;
}
- rpi_domains->fw = rpi_firmware_get(fw_np);
+ rpi_domains->fw = devm_rpi_firmware_get(&pdev->dev, fw_np);
of_node_put(fw_np);
if (!rpi_domains->fw)
return -EPROBE_DEFER;
--
2.29.1
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 <[email protected]>
---
Changes since v2:
- Use devm_rpi_firmware_get()
- Rename driver
- Small cleanups as per Andy Shevchenko's comments
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 | 216 ++++++++++++++++++++++++++++++
3 files changed, 226 insertions(+)
create mode 100644 drivers/pwm/pwm-raspberrypi-poe.c
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 63be5362fd3a..ab31615f07fc 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -379,6 +379,15 @@ 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 cbdcd55d69ee..7ecbbbcb323a 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
obj-$(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..91cd826a36f3
--- /dev/null
+++ b/drivers/pwm/pwm-raspberrypi-poe.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Nicolas Saenz Julienne <[email protected]>
+ * 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-pwm.h>
+
+#define RPI_PWM_MAX_DUTY 255
+#define RPI_PWM_PERIOD_NS 80000 /* 12.5 kHz */
+
+#define RPI_PWM_CUR_DUTY_REG 0x0
+#define RPI_PWM_DEF_DUTY_REG 0x1
+
+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 *to_raspberrypi_pwm(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 = to_raspberrypi_pwm(chip);
+
+ state->period = RPI_PWM_PERIOD_NS;
+ state->duty_cycle = DIV_ROUND_CLOSEST(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 = to_raspberrypi_pwm(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_CLOSEST_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: %d\n", ret);
+ return ret;
+ }
+
+ /*
+ * This sets the default duty cycle after resetting the board, we
+ * updated it every time to mimic Raspberry Pi's downstream's driver
+ * behaviour.
+ */
+ ret = raspberrypi_pwm_set_property(rpipwm->firmware, RPI_PWM_DEF_DUTY_REG,
+ duty_cycle);
+ if (ret) {
+ dev_err(chip->dev, "Failed to set default duty cycle: %d\n", 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 -EPROBE_DEFER;
+
+ 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: %d\n", 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-pwm", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, raspberrypi_pwm_of_match);
+
+static struct platform_driver raspberrypi_pwm_driver = {
+ .driver = {
+ .name = "raspberrypi-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 <[email protected]>");
+MODULE_DESCRIPTION("Raspberry Pi Firwmare Based PWM Bus Driver");
+MODULE_LICENSE("GPL v2");
--
2.29.1
This is an example on how to enable the fan on top of RPi's official PoE
hat.
Signed-off-by: Nicolas Saenz Julienne <[email protected]>
---
Changes since v1:
- Update patch to use 2 pwm cells
arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 54 +++++++++++++++++++++++++++
1 file changed, 54 insertions(+)
diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
index 09a1182c2936..361db82619a4 100644
--- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
@@ -5,6 +5,7 @@
#include "bcm283x-rpi-usb-peripheral.dtsi"
#include <dt-bindings/reset/raspberrypi,firmware-reset.h>
+#include <dt-bindings/pwm/raspberrypi,firmware-pwm.h>
/ {
compatible = "raspberrypi,4-model-b", "brcm,bcm2711";
@@ -68,6 +69,54 @@ sd_vcc_reg: sd_vcc_reg {
enable-active-high;
gpio = <&expgpio 6 GPIO_ACTIVE_HIGH>;
};
+
+ fan: pwm-fan {
+ compatible = "pwm-fan";
+ cooling-levels = <0 50 150 255>;
+ #cooling-cells = <2>;
+ pwms = <&fwpwm RASPBERRYPI_FIRMWARE_PWM_POE 80000>;
+ };
+
+ thermal-zones {
+ cpu_thermal: cpu-thermal {
+ trips {
+ threshold: trip-point@0 {
+ temperature = <45000>;
+ hysteresis = <5000>;
+ type = "active";
+ };
+
+ target: trip-point@1 {
+ temperature = <50000>;
+ hysteresis = <2000>;
+ type = "active";
+ };
+
+ cpu_hot: cpu_hot@0 {
+ temperature = <55000>;
+ hysteresis = <2000>;
+ type = "active";
+ };
+ };
+
+ cooling-maps {
+ map0 {
+ trip = <&threshold>;
+ cooling-device = <&fan 0 1>;
+ };
+
+ map1 {
+ trip = <&target>;
+ cooling-device = <&fan 1 2>;
+ };
+
+ map2 {
+ trip = <&cpu_hot>;
+ cooling-device = <&fan 2 3>;
+ };
+ };
+ };
+ };
};
&ddc0 {
@@ -103,6 +152,11 @@ reset: reset {
compatible = "raspberrypi,firmware-reset";
#reset-cells = <1>;
};
+
+ fwpwm: pwm {
+ compatible = "raspberrypi,firmware-pwm";
+ #pwm-cells = <2>;
+ };
};
&gpio {
--
2.29.1
Use devm_rpi_firmware_get() so as to make sure we release RPi's firmware
interface when unbinding the device.
Signed-off-by: Nicolas Saenz Julienne <[email protected]>
---
Changes since v2:
- Use devm_rpi_firmware_get(), instead of remove function
drivers/input/touchscreen/raspberrypi-ts.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/input/touchscreen/raspberrypi-ts.c b/drivers/input/touchscreen/raspberrypi-ts.c
index ef6aaed217cf..efed0efa91d9 100644
--- a/drivers/input/touchscreen/raspberrypi-ts.c
+++ b/drivers/input/touchscreen/raspberrypi-ts.c
@@ -134,7 +134,7 @@ static int rpi_ts_probe(struct platform_device *pdev)
return -ENOENT;
}
- fw = rpi_firmware_get(fw_node);
+ fw = devm_rpi_firmware_get(&pdev->dev, fw_node);
of_node_put(fw_node);
if (!fw)
return -EPROBE_DEFER;
--
2.29.1
Hi Nicolas,
On Wed, Nov 04, 2020 at 11:39:33AM +0100, Nicolas Saenz Julienne wrote:
> Use devm_rpi_firmware_get() so as to make sure we release RPi's firmware
> interface when unbinding the device.
Unless I am mistaken this driver does not really need the firmware
structure past rpi_ts_probe(), and will be fine if it disappears earlier
than unbind time.
Thanks.
>
> Signed-off-by: Nicolas Saenz Julienne <[email protected]>
>
> ---
>
> Changes since v2:
> - Use devm_rpi_firmware_get(), instead of remove function
>
> drivers/input/touchscreen/raspberrypi-ts.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/input/touchscreen/raspberrypi-ts.c b/drivers/input/touchscreen/raspberrypi-ts.c
> index ef6aaed217cf..efed0efa91d9 100644
> --- a/drivers/input/touchscreen/raspberrypi-ts.c
> +++ b/drivers/input/touchscreen/raspberrypi-ts.c
> @@ -134,7 +134,7 @@ static int rpi_ts_probe(struct platform_device *pdev)
> return -ENOENT;
> }
>
> - fw = rpi_firmware_get(fw_node);
> + fw = devm_rpi_firmware_get(&pdev->dev, fw_node);
> of_node_put(fw_node);
> if (!fw)
> return -EPROBE_DEFER;
> --
> 2.29.1
>
--
Dmitry
On Wed, 2020-11-11 at 17:45 -0800, Dmitry Torokhov wrote:
> Hi Nicolas,
>
> On Wed, Nov 04, 2020 at 11:39:33AM +0100, Nicolas Saenz Julienne wrote:
> > Use devm_rpi_firmware_get() so as to make sure we release RPi's firmware
> > interface when unbinding the device.
>
> Unless I am mistaken this driver does not really need the firmware
> structure past rpi_ts_probe(), and will be fine if it disappears earlier
> than unbind time.
Yes, I missed that. Will update it.
Regards,
Nicolas