[PATCH v2 00/10] Raspberry Pi PoE HAT fan support

[PATCH v2 00/10] Raspberry Pi PoE HAT fan support

[Nicolas Saenz Julienne]

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 v1:
 - Address PWM driver changes
 - Fix binding, now with 2 cells
 - Add reference count to rpi_firmware_get()

Nicolas Saenz Julienne (10):
  firmware: raspberrypi: Introduce rpi_firmware_put()
  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
  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             |   1 +
 drivers/firmware/raspberrypi.c                |  30 ++-
 drivers/gpio/gpio-raspberrypi-exp.c           |  14 +-
 drivers/input/touchscreen/raspberrypi-ts.c    |   1 +
 drivers/pwm/Kconfig                           |   9 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-raspberrypi.c                 | 221 ++++++++++++++++++
 drivers/reset/reset-raspberrypi.c             |  13 +-
 drivers/soc/bcm/raspberrypi-power.c           |  15 ++
 .../interface/vchiq_arm/vchiq_arm.c           |   3 +
 .../pwm/raspberrypi,firmware-pwm.h            |  13 ++
 include/soc/bcm2835/raspberrypi-firmware.h    |   3 +
 14 files changed, 395 insertions(+), 3 deletions(-)
 create mode 100644 drivers/pwm/pwm-raspberrypi.c
 create mode 100644 include/dt-bindings/pwm/raspberrypi,firmware-pwm.h

-- 
2.28.0

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[PATCH v2 01/10] firmware: raspberrypi: Introduce rpi_firmware_put()

[Nicolas Saenz Julienne]

When unbinding the firmware device we need to make sure it has no
consumers left. Otherwise we'd leave them with a firmware handle
pointing at freed memory.

Keep a reference count of all consumers and make sure they all finished
unbinding before we do.

Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---

@Uwe: I didn't found it necessary to call 'try_module_get()' as the rest
      of modules depend on the 'rpi_firmware_get/put()' symbols which already
      block users from unloading the module prematurely.

 drivers/firmware/raspberrypi.c             | 30 +++++++++++++++++++++-
 include/soc/bcm2835/raspberrypi-firmware.h |  3 +++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 2371d08bdd17..e5ba609e3985 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -11,7 +11,9 @@
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/refcount.h>
 #include <linux/slab.h>
+#include <linux/wait.h>
 #include <soc/bcm2835/raspberrypi-firmware.h>
 
 #define MBOX_MSG(chan, data28)		(((data28) & ~0xf) | ((chan) & 0xf))
@@ -27,6 +29,9 @@ struct rpi_firmware {
 	struct mbox_chan *chan; /* The property channel. */
 	struct completion c;
 	u32 enabled;
+
+	refcount_t consumers;
+	wait_queue_head_t wait;
 };
 
 static DEFINE_MUTEX(transaction_lock);
@@ -247,6 +252,8 @@ static int rpi_firmware_probe(struct platform_device *pdev)
 	}
 
 	init_completion(&fw->c);
+	refcount_set(&fw->consumers, 1);
+	init_waitqueue_head(&fw->wait);
 
 	platform_set_drvdata(pdev, fw);
 
@@ -275,6 +282,8 @@ static int rpi_firmware_remove(struct platform_device *pdev)
 	rpi_hwmon = NULL;
 	platform_device_unregister(rpi_clk);
 	rpi_clk = NULL;
+
+	wait_event(fw->wait, refcount_dec_if_one(&fw->consumers));
 	mbox_free_channel(fw->chan);
 
 	return 0;
@@ -289,14 +298,33 @@ static int rpi_firmware_remove(struct platform_device *pdev)
 struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
 {
 	struct platform_device *pdev = of_find_device_by_node(firmware_node);
+	struct rpi_firmware *fw;
 
 	if (!pdev)
 		return NULL;
 
-	return platform_get_drvdata(pdev);
+	fw = platform_get_drvdata(pdev);
+	if (!fw)
+		return NULL;
+
+	if (!refcount_inc_not_zero(&fw->consumers))
+		return NULL;
+
+	return fw;
 }
 EXPORT_SYMBOL_GPL(rpi_firmware_get);
 
+/**
+ * rpi_firmware_put - Put pointer to rpi_firmware structure.
+ * @rpi_firmware:    Pointer to struct rpi_firmware
+ */
+void rpi_firmware_put(struct rpi_firmware *fw)
+{
+	refcount_dec(&fw->consumers);
+	wake_up(&fw->wait);
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_put);
+
 static const struct of_device_id rpi_firmware_of_match[] = {
 	{ .compatible = "raspberrypi,bcm2835-firmware", },
 	{},
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index cc9cdbc66403..7836ea51fbdf 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -141,6 +141,7 @@ int rpi_firmware_property(struct rpi_firmware *fw,
 int rpi_firmware_property_list(struct rpi_firmware *fw,
 			       void *data, size_t tag_size);
 struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node);
+void rpi_firmware_put(struct rpi_firmware *fw);
 #else
 static inline int rpi_firmware_property(struct rpi_firmware *fw, u32 tag,
 					void *data, size_t len)
@@ -158,6 +159,8 @@ static inline struct rpi_firmware *rpi_firmware_get(struct device_node *firmware
 {
 	return NULL;
 }
+
+void rpi_firmware_put(struct rpi_firmware *fw) { }
 #endif
 
 #endif /* __SOC_RASPBERRY_FIRMWARE_H__ */
-- 
2.28.0

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[PATCH v2 02/10] clk: bcm: rpi: Release firmware handle on unbind

[Nicolas Saenz Julienne]

Upon unbinding the clock device make sure we release RPi's firmware
interface.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/clk/bcm/clk-raspberrypi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
index f89b9cfc4309..845510ff7514 100644
--- a/drivers/clk/bcm/clk-raspberrypi.c
+++ b/drivers/clk/bcm/clk-raspberrypi.c
@@ -353,6 +353,7 @@ static int raspberrypi_clk_remove(struct platform_device *pdev)
 	struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);
 
 	platform_device_unregister(rpi->cpufreq);
+	rpi_firmware_put(rpi->firmware);
 
 	return 0;
 }
-- 
2.28.0

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[PATCH v2 03/10] gpio: raspberrypi-exp: Release firmware handle on unbind

[Nicolas Saenz Julienne]

Upon unbinding the device make sure we release RPi's firmware interface.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/gpio/gpio-raspberrypi-exp.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-raspberrypi-exp.c b/drivers/gpio/gpio-raspberrypi-exp.c
index bb100e0124e6..c008336e1131 100644
--- a/drivers/gpio/gpio-raspberrypi-exp.c
+++ b/drivers/gpio/gpio-raspberrypi-exp.c
@@ -231,8 +231,19 @@ static int rpi_exp_gpio_probe(struct platform_device *pdev)
 	rpi_gpio->gc.get = rpi_exp_gpio_get;
 	rpi_gpio->gc.set = rpi_exp_gpio_set;
 	rpi_gpio->gc.can_sleep = true;
+	platform_set_drvdata(pdev, rpi_gpio);
 
-	return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
+	return gpiochip_add_data(&rpi_gpio->gc, rpi_gpio);
+}
+
+static int rpi_exp_gpio_remove(struct platform_device *pdev)
+{
+	struct rpi_exp_gpio *rpi_gpio = platform_get_drvdata(pdev);
+
+	gpiochip_remove(&rpi_gpio->gc);
+	rpi_firmware_put(rpi_gpio->fw);
+
+	return 0;
 }
 
 static const struct of_device_id rpi_exp_gpio_ids[] = {
@@ -247,6 +258,7 @@ static struct platform_driver rpi_exp_gpio_driver = {
 		.of_match_table	= of_match_ptr(rpi_exp_gpio_ids),
 	},
 	.probe	= rpi_exp_gpio_probe,
+	.remove = rpi_exp_gpio_remove,
 };
 module_platform_driver(rpi_exp_gpio_driver);
 
-- 
2.28.0

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[PATCH v2 04/10] reset: raspberrypi: Release firmware handle on unbind

[Nicolas Saenz Julienne]

Upon unbinding the device make sure we release RPi's firmware interface.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/reset/reset-raspberrypi.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/reset/reset-raspberrypi.c b/drivers/reset/reset-raspberrypi.c
index 02f59c06f69b..29311192e2c9 100644
--- a/drivers/reset/reset-raspberrypi.c
+++ b/drivers/reset/reset-raspberrypi.c
@@ -99,7 +99,17 @@ static int rpi_reset_probe(struct platform_device *pdev)
 	priv->rcdev.ops = &rpi_reset_ops;
 	priv->rcdev.of_node = dev->of_node;
 
-	return devm_reset_controller_register(dev, &priv->rcdev);
+	return reset_controller_register(&priv->rcdev);
+}
+
+static int rpi_reset_remove(struct platform_device *pdev)
+{
+	struct rpi_reset *priv = platform_get_drvdata(pdev);
+
+	reset_controller_unregister(&priv->rcdev);
+	rpi_firmware_put(priv->fw);
+
+	return 0;
 }
 
 static const struct of_device_id rpi_reset_of_match[] = {
@@ -110,6 +120,7 @@ MODULE_DEVICE_TABLE(of, rpi_reset_of_match);
 
 static struct platform_driver rpi_reset_driver = {
 	.probe	= rpi_reset_probe,
+	.remove	= rpi_reset_remove,
 	.driver	= {
 		.name = "raspberrypi-reset",
 		.of_match_table = rpi_reset_of_match,
-- 
2.28.0

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[PATCH v2 05/10] soc: bcm: raspberrypi-power: Release firmware handle on unbind

[Nicolas Saenz Julienne]

Upon unbinding the device make sure we release RPi's firmware interface.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/soc/bcm/raspberrypi-power.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/soc/bcm/raspberrypi-power.c b/drivers/soc/bcm/raspberrypi-power.c
index 5d1aacdd84ef..a0b38db5886c 100644
--- a/drivers/soc/bcm/raspberrypi-power.c
+++ b/drivers/soc/bcm/raspberrypi-power.c
@@ -225,6 +225,20 @@ static int rpi_power_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int rpi_power_remove(struct platform_device *pdev)
+{
+	struct rpi_power_domains *rpi_domains = platform_get_drvdata(pdev);
+
+	of_genpd_del_provider(dev->of_node);
+
+	for (i = 0; i < RPI_POWER_DOMAIN_COUNT; i++)
+		pm_genpd_remove(&rpi_domains->domains[i].base);
+
+	rpi_firmware_put(rpi_domaina->fw);
+
+	return 0;
+}
+
 static const struct of_device_id rpi_power_of_match[] = {
 	{ .compatible = "raspberrypi,bcm2835-power", },
 	{},
@@ -237,6 +251,7 @@ static struct platform_driver rpi_power_driver = {
 		.of_match_table = rpi_power_of_match,
 	},
 	.probe		= rpi_power_probe,
+	.remove		= rpi_power_remove,
 };
 builtin_platform_driver(rpi_power_driver);
 
-- 
2.28.0

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[PATCH v2 06/10] staging: vchiq: Release firmware handle on unbind

[Nicolas Saenz Julienne]

Upon unbinding the device make sure we release RPi's firmware interface.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index 01125d9f991b..dfa4d144faa8 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -2771,11 +2771,14 @@ static int vchiq_probe(struct platform_device *pdev)
 
 static int vchiq_remove(struct platform_device *pdev)
 {
+	struct vchiq_drvdata *drvdata = platform_get_drvdata(pdev);
+
 	platform_device_unregister(bcm2835_audio);
 	platform_device_unregister(bcm2835_camera);
 	vchiq_debugfs_deinit();
 	device_destroy(vchiq_class, vchiq_devid);
 	cdev_del(&vchiq_cdev);
+	rpi_firmware_put(drvdata->fw);
 
 	return 0;
 }
-- 
2.28.0

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[PATCH v2 07/10] input: raspberrypi-ts: Release firmware handle when not needed

[Nicolas Saenz Julienne]

After passing the DMA buffer address through the firmware interface,
release the firmware handle, we won't need it anymore.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
 drivers/input/touchscreen/raspberrypi-ts.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/input/touchscreen/raspberrypi-ts.c b/drivers/input/touchscreen/raspberrypi-ts.c
index ef6aaed217cf..29c878a00018 100644
--- a/drivers/input/touchscreen/raspberrypi-ts.c
+++ b/drivers/input/touchscreen/raspberrypi-ts.c
@@ -165,6 +165,7 @@ static int rpi_ts_probe(struct platform_device *pdev)
 		dev_warn(dev, "Failed to set touchbuf, %d\n", error);
 		return error;
 	}
+	rpi_firmware_put(fw);
 
 	input = devm_input_allocate_device(dev);
 	if (!input) {
-- 
2.28.0

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[PATCH v2 08/10] dt-bindings: pwm: Add binding for RPi firmware PWM bus

[Nicolas Saenz Julienne]

The PWM bus controlling the fan in RPi's official PoE hat can only be
controlled by the board's co-processor.

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

---
Changes since v1:
 - Update bindings to use 2 #pwm-cells

 .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 20 +++++++++++++++++++
 .../pwm/raspberrypi,firmware-pwm.h            | 13 ++++++++++++
 2 files changed, 33 insertions(+)
 create mode 100644 include/dt-bindings/pwm/raspberrypi,firmware-pwm.h

diff --git a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
index a2c63c8b1d10..8029ce958c48 100644
--- a/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
+++ b/Documentation/devicetree/bindings/arm/bcm/raspberrypi,bcm2835-firmware.yaml
@@ -64,6 +64,21 @@ properties:
       - compatible
       - "#reset-cells"
 
+  pwm:
+    type: object
+
+    properties:
+      compatible:
+        const: raspberrypi,firmware-pwm
+
+      "#pwm-cells":
+        # See pwm.yaml in this directory for a description of the cells format.
+        const: 2
+
+    required:
+      - compatible
+      - "#pwm-cells"
+
     additionalProperties: false
 
 required:
@@ -87,5 +102,10 @@ examples:
             compatible = "raspberrypi,firmware-reset";
             #reset-cells = <1>;
         };
+
+        pwm: pwm {
+            compatible = "raspberrypi,firmware-pwm";
+            #pwm-cells = <1>;
+        };
     };
 ...
diff --git a/include/dt-bindings/pwm/raspberrypi,firmware-pwm.h b/include/dt-bindings/pwm/raspberrypi,firmware-pwm.h
new file mode 100644
index 000000000000..27c5ce68847b
--- /dev/null
+++ b/include/dt-bindings/pwm/raspberrypi,firmware-pwm.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2020 Nicolas Saenz Julienne
+ * Author: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ */
+
+#ifndef _DT_BINDINGS_RASPBERRYPI_FIRMWARE_PWM_H
+#define _DT_BINDINGS_RASPBERRYPI_FIRMWARE_PWM_H
+
+#define RASPBERRYPI_FIRMWARE_PWM_POE		0
+#define RASPBERRYPI_FIRMWARE_PWM_NUM		1
+
+#endif
-- 
2.28.0

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[PATCH v2 09/10] DO NOT MERGE: ARM: dts: Add RPi's official PoE hat support

[Nicolas Saenz Julienne]

This is an example on how to enable the fan on top of RPi's official PoE
hat.

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

---

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 {
-- 
2.28.0

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[PATCH v2 10/10] pwm: Add Raspberry Pi Firmware based PWM bus

[Nicolas Saenz Julienne]

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 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
 - Add comment explaining weird Kconfig construct

 drivers/pwm/Kconfig           |   9 ++
 drivers/pwm/Makefile          |   1 +
 drivers/pwm/pwm-raspberrypi.c | 221 ++++++++++++++++++++++++++++++++++
 3 files changed, 231 insertions(+)
 create mode 100644 drivers/pwm/pwm-raspberrypi.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 63be5362fd3a..b0ffb1e690c0 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
+	tristate "Raspberry Pi Firwmware 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..b557b549d9f3 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-$(CONFIG_PWM_RASPBERRYPI)	+= pwm-raspberrypi.o
 obj-$(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.c b/drivers/pwm/pwm-raspberrypi.c
new file mode 100644
index 000000000000..72dc0fc5a206
--- /dev/null
+++ b/drivers/pwm/pwm-raspberrypi.c
@@ -0,0 +1,221 @@
+// 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-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;
+	else 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;
+	else 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 = rpi_firmware_get(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);
+	int ret;
+
+	ret = pwmchip_remove(&rpipwm->chip);
+	if (!ret)
+		rpi_firmware_put(rpipwm->firmware);
+
+	return ret;
+}
+
+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 <nsaenzjulienne@suse.de>");
+MODULE_DESCRIPTION("Raspberry Pi Firwmare Based PWM Bus Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.28.0

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Re: [PATCH v2 01/10] firmware: raspberrypi: Introduce rpi_firmware_put()

[Andy Shevchenko]

On Thu, Oct 22, 2020 at 9:06 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> When unbinding the firmware device we need to make sure it has no
> consumers left. Otherwise we'd leave them with a firmware handle
> pointing at freed memory.
>
> Keep a reference count of all consumers and make sure they all finished
> unbinding before we do.

Wait, if it's a device, why do we need all these?
get_device() / put_device() along with module_get() / module_put()
should be sufficient, no?

-- 
With Best Regards,
Andy Shevchenko
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Re: [PATCH v2 10/10] pwm: Add Raspberry Pi Firmware based PWM bus

[Andy Shevchenko]

On Thu, Oct 22, 2020 at 9:05 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> 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.

>  drivers/pwm/pwm-raspberrypi.c | 221 ++++++++++++++++++++++++++++++++++

Name is completely confusing.
Please, make it unique enough to understand that this is exactly the
device it serves for.

For example, pwm-rpi-poe is better.

...

> + *  - Only normal polarity

Can't it be emulated? Isn't it 100% - duty cycle % ?


> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pwm.h>

...

> +       ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL,
> +                                   &msg, sizeof(msg));
> +       if (ret)
> +               return ret;

> +       else if (msg.ret)

Redundant 'else'

> +               return -EIO;

...

> +       ret = rpi_firmware_property(firmware, RPI_FIRMWARE_GET_POE_HAT_VAL,
> +                                   &msg, sizeof(msg));
> +       if (ret)
> +               return ret;

> +       else if (msg.ret)

Ditto.

> +               return -EIO;

...

> +       firmware_node = of_get_parent(dev->of_node);
> +       if (!firmware_node) {
> +               dev_err(dev, "Missing firmware node\n");
> +               return -ENOENT;
> +       }
> +
> +       firmware = rpi_firmware_get(firmware_node);
> +       of_node_put(firmware_node);
> +       if (!firmware)
> +               return -EPROBE_DEFER;

Looks like a hack.

...

> +       ret = pwmchip_remove(&rpipwm->chip);
> +       if (!ret)
> +               rpi_firmware_put(rpipwm->firmware);
> +
> +       return ret;

Can't you use the usual pattern?

  ret = ...
  if (ret)
    return ret;
  ...
  return 0;

-- 
With Best Regards,
Andy Shevchenko
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Re: [PATCH v2 10/10] pwm: Add Raspberry Pi Firmware based PWM bus

[Nicolas Saenz Julienne]

[-- Attachment #1.1: Type: text/plain, Size: 2155 bytes --]

Hi Andy, thanks for the review!

On Thu, 2020-10-22 at 21:53 +0300, Andy Shevchenko wrote:
> On Thu, Oct 22, 2020 at 9:05 PM Nicolas Saenz Julienne
> <nsaenzjulienne@suse.de> 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.
> >  drivers/pwm/pwm-raspberrypi.c | 221 ++++++++++++++++++++++++++++++++++
> 
> Name is completely confusing.
> Please, make it unique enough to understand that this is exactly the
> device it serves for.
> 
> For example, pwm-rpi-poe is better.

Sounds reasonable, I'll change that.

> 
> ...
> 
> > + *  - Only normal polarity
> 
> Can't it be emulated? Isn't it 100% - duty cycle % ?

I guess it can, OTOH given the rather specific use case, I doubt it'll be
worth the effort.

> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pwm.h>
> 
> ...
> 
> > +       ret = rpi_firmware_property(firmware, RPI_FIRMWARE_SET_POE_HAT_VAL,
> > +                                   &msg, sizeof(msg));
> > +       if (ret)
> > +               return ret;
> > +       else if (msg.ret)
> 
> Redundant 'else'

Noted.

> > +       firmware_node = of_get_parent(dev->of_node);
> > +       if (!firmware_node) {
> > +               dev_err(dev, "Missing firmware node\n");
> > +               return -ENOENT;
> > +       }
> > +
> > +       firmware = rpi_firmware_get(firmware_node);
> > +       of_node_put(firmware_node);
> > +       if (!firmware)
> > +               return -EPROBE_DEFER;
> 
> Looks like a hack.

This is the pattern we've been using on all firmware dependent devices so far.
Feel free to suggest a better way, I'll be happy to look into it.

> 
> ...
> 
> > +       ret = pwmchip_remove(&rpipwm->chip);
> > +       if (!ret)
> > +               rpi_firmware_put(rpipwm->firmware);
> > +
> > +       return ret;
> 
> Can't you use the usual pattern?

Yes of course. Don't know why I went this way.

Regards,
Nicolas


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Re: [PATCH v2 05/10] soc: bcm: raspberrypi-power: Release firmware handle on unbind

[Nicolas Saenz Julienne]

[-- Attachment #1.1: Type: text/plain, Size: 1525 bytes --]

On Thu, 2020-10-22 at 17:58 +0200, Nicolas Saenz Julienne wrote:
> Upon unbinding the device make sure we release RPi's firmware interface.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---
>  drivers/soc/bcm/raspberrypi-power.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/soc/bcm/raspberrypi-power.c b/drivers/soc/bcm/raspberrypi-power.c
> index 5d1aacdd84ef..a0b38db5886c 100644
> --- a/drivers/soc/bcm/raspberrypi-power.c
> +++ b/drivers/soc/bcm/raspberrypi-power.c
> @@ -225,6 +225,20 @@ static int rpi_power_probe(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +static int rpi_power_remove(struct platform_device *pdev)
> +{
> +	struct rpi_power_domains *rpi_domains = platform_get_drvdata(pdev);
> +
> +	of_genpd_del_provider(dev->of_node);
> +
> +	for (i = 0; i < RPI_POWER_DOMAIN_COUNT; i++)
> +		pm_genpd_remove(&rpi_domains->domains[i].base);
> +
> +	rpi_firmware_put(rpi_domaina->fw);

I Just realised I failed to squash a fix for this patch, so this will not
build. Sorry for that.

Regards,
Nicolas

> +
> +	return 0;
> +}
> +
>  static const struct of_device_id rpi_power_of_match[] = {
>  	{ .compatible = "raspberrypi,bcm2835-power", },
>  	{},
> @@ -237,6 +251,7 @@ static struct platform_driver rpi_power_driver = {
>  		.of_match_table = rpi_power_of_match,
>  	},
>  	.probe		= rpi_power_probe,
> +	.remove		= rpi_power_remove,
>  };
>  builtin_platform_driver(rpi_power_driver);
>  


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Re: [PATCH v2 03/10] gpio: raspberrypi-exp: Release firmware handle on unbind

[Bartosz Golaszewski]

On Thu, Oct 22, 2020 at 5:59 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> Upon unbinding the device make sure we release RPi's firmware interface.
>
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> ---
>  drivers/gpio/gpio-raspberrypi-exp.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-raspberrypi-exp.c b/drivers/gpio/gpio-raspberrypi-exp.c
> index bb100e0124e6..c008336e1131 100644
> --- a/drivers/gpio/gpio-raspberrypi-exp.c
> +++ b/drivers/gpio/gpio-raspberrypi-exp.c
> @@ -231,8 +231,19 @@ static int rpi_exp_gpio_probe(struct platform_device *pdev)
>         rpi_gpio->gc.get = rpi_exp_gpio_get;
>         rpi_gpio->gc.set = rpi_exp_gpio_set;
>         rpi_gpio->gc.can_sleep = true;
> +       platform_set_drvdata(pdev, rpi_gpio);
>
> -       return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
> +       return gpiochip_add_data(&rpi_gpio->gc, rpi_gpio);
> +}
> +
> +static int rpi_exp_gpio_remove(struct platform_device *pdev)
> +{
> +       struct rpi_exp_gpio *rpi_gpio = platform_get_drvdata(pdev);
> +
> +       gpiochip_remove(&rpi_gpio->gc);
> +       rpi_firmware_put(rpi_gpio->fw);
> +
> +       return 0;
>  }
>
>  static const struct of_device_id rpi_exp_gpio_ids[] = {
> @@ -247,6 +258,7 @@ static struct platform_driver rpi_exp_gpio_driver = {
>                 .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
>         },
>         .probe  = rpi_exp_gpio_probe,
> +       .remove = rpi_exp_gpio_remove,
>  };
>  module_platform_driver(rpi_exp_gpio_driver);
>
> --
> 2.28.0
>

Why not introduce devm_rpi_firmware_get()? That would allow you to
keep the driver elegant without re-adding remove().

Bartosz
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Re: [PATCH v2 03/10] gpio: raspberrypi-exp: Release firmware handle on unbind

[Nicolas Saenz Julienne]

[-- Attachment #1.1: Type: text/plain, Size: 1996 bytes --]

On Mon, 2020-10-26 at 15:40 +0100, Bartosz Golaszewski wrote:
> On Thu, Oct 22, 2020 at 5:59 PM Nicolas Saenz Julienne
> <nsaenzjulienne@suse.de> wrote:
> > Upon unbinding the device make sure we release RPi's firmware interface.
> > 
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > ---
> >  drivers/gpio/gpio-raspberrypi-exp.c | 14 +++++++++++++-
> >  1 file changed, 13 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpio/gpio-raspberrypi-exp.c b/drivers/gpio/gpio-raspberrypi-exp.c
> > index bb100e0124e6..c008336e1131 100644
> > --- a/drivers/gpio/gpio-raspberrypi-exp.c
> > +++ b/drivers/gpio/gpio-raspberrypi-exp.c
> > @@ -231,8 +231,19 @@ static int rpi_exp_gpio_probe(struct platform_device *pdev)
> >         rpi_gpio->gc.get = rpi_exp_gpio_get;
> >         rpi_gpio->gc.set = rpi_exp_gpio_set;
> >         rpi_gpio->gc.can_sleep = true;
> > +       platform_set_drvdata(pdev, rpi_gpio);
> > 
> > -       return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
> > +       return gpiochip_add_data(&rpi_gpio->gc, rpi_gpio);
> > +}
> > +
> > +static int rpi_exp_gpio_remove(struct platform_device *pdev)
> > +{
> > +       struct rpi_exp_gpio *rpi_gpio = platform_get_drvdata(pdev);
> > +
> > +       gpiochip_remove(&rpi_gpio->gc);
> > +       rpi_firmware_put(rpi_gpio->fw);
> > +
> > +       return 0;
> >  }
> > 
> >  static const struct of_device_id rpi_exp_gpio_ids[] = {
> > @@ -247,6 +258,7 @@ static struct platform_driver rpi_exp_gpio_driver = {
> >                 .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
> >         },
> >         .probe  = rpi_exp_gpio_probe,
> > +       .remove = rpi_exp_gpio_remove,
> >  };
> >  module_platform_driver(rpi_exp_gpio_driver);
> > 
> > --
> > 2.28.0
> > 
> 
> Why not introduce devm_rpi_firmware_get()? That would allow you to
> keep the driver elegant without re-adding remove().

I like the idea, I'll look into it.

Thanks,
Nicolas


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Re: [PATCH v2 03/10] gpio: raspberrypi-exp: Release firmware handle on unbind

[Bartosz Golaszewski]

On Mon, Oct 26, 2020 at 3:42 PM Nicolas Saenz Julienne
<nsaenzjulienne@suse.de> wrote:
>
> On Mon, 2020-10-26 at 15:40 +0100, Bartosz Golaszewski wrote:
> > On Thu, Oct 22, 2020 at 5:59 PM Nicolas Saenz Julienne
> > <nsaenzjulienne@suse.de> wrote:
> > > Upon unbinding the device make sure we release RPi's firmware interface.
> > >
> > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> > > ---
> > >  drivers/gpio/gpio-raspberrypi-exp.c | 14 +++++++++++++-
> > >  1 file changed, 13 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpio/gpio-raspberrypi-exp.c b/drivers/gpio/gpio-raspberrypi-exp.c
> > > index bb100e0124e6..c008336e1131 100644
> > > --- a/drivers/gpio/gpio-raspberrypi-exp.c
> > > +++ b/drivers/gpio/gpio-raspberrypi-exp.c
> > > @@ -231,8 +231,19 @@ static int rpi_exp_gpio_probe(struct platform_device *pdev)
> > >         rpi_gpio->gc.get = rpi_exp_gpio_get;
> > >         rpi_gpio->gc.set = rpi_exp_gpio_set;
> > >         rpi_gpio->gc.can_sleep = true;
> > > +       platform_set_drvdata(pdev, rpi_gpio);
> > >
> > > -       return devm_gpiochip_add_data(dev, &rpi_gpio->gc, rpi_gpio);
> > > +       return gpiochip_add_data(&rpi_gpio->gc, rpi_gpio);
> > > +}
> > > +
> > > +static int rpi_exp_gpio_remove(struct platform_device *pdev)
> > > +{
> > > +       struct rpi_exp_gpio *rpi_gpio = platform_get_drvdata(pdev);
> > > +
> > > +       gpiochip_remove(&rpi_gpio->gc);
> > > +       rpi_firmware_put(rpi_gpio->fw);
> > > +
> > > +       return 0;
> > >  }
> > >
> > >  static const struct of_device_id rpi_exp_gpio_ids[] = {
> > > @@ -247,6 +258,7 @@ static struct platform_driver rpi_exp_gpio_driver = {
> > >                 .of_match_table = of_match_ptr(rpi_exp_gpio_ids),
> > >         },
> > >         .probe  = rpi_exp_gpio_probe,
> > > +       .remove = rpi_exp_gpio_remove,
> > >  };
> > >  module_platform_driver(rpi_exp_gpio_driver);
> > >
> > > --
> > > 2.28.0
> > >
> >
> > Why not introduce devm_rpi_firmware_get()? That would allow you to
> > keep the driver elegant without re-adding remove().
>
> I like the idea, I'll look into it.
>
> Thanks,
> Nicolas
>

If you can't do it for some reason, then even using devm_add_action() is fine.

Bartosz
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Re: [PATCH v2 01/10] firmware: raspberrypi: Introduce rpi_firmware_put()

[Nicolas Saenz Julienne]

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On Thu, 2020-10-22 at 21:46 +0300, Andy Shevchenko wrote:
> On Thu, Oct 22, 2020 at 9:06 PM Nicolas Saenz Julienne
> <nsaenzjulienne@suse.de> wrote:
> > When unbinding the firmware device we need to make sure it has no
> > consumers left. Otherwise we'd leave them with a firmware handle
> > pointing at freed memory.
> > 
> > Keep a reference count of all consumers and make sure they all finished
> > unbinding before we do.
> 
> Wait, if it's a device, why do we need all these?
> get_device() / put_device() along with module_get() / module_put()
> should be sufficient, no?

Could you expand here a little, I do see how I could use get_device()'s
reference count. But it seems to me I'd be digging way too deep into kobj in
order to get the functionality I need.

If you meant to say that it should be automatically taken care by the platform
bus, just FYI we're using 'simple-mfd' in DT. Where firmware supplier is the
parent and all consumers are children.

Regards,
Nicolas


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Re: [PATCH v2 08/10] dt-bindings: pwm: Add binding for RPi firmware PWM bus

[Rob Herring]

On Thu, 22 Oct 2020 17:58:55 +0200, Nicolas Saenz Julienne wrote:
> The PWM bus controlling the fan in RPi's official PoE hat can only be
> controlled by the board's co-processor.
> 
> Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
> 
> ---
> Changes since v1:
>  - Update bindings to use 2 #pwm-cells
> 
>  .../arm/bcm/raspberrypi,bcm2835-firmware.yaml | 20 +++++++++++++++++++
>  .../pwm/raspberrypi,firmware-pwm.h            | 13 ++++++++++++
>  2 files changed, 33 insertions(+)
>  create mode 100644 include/dt-bindings/pwm/raspberrypi,firmware-pwm.h
> 

Reviewed-by: Rob Herring <robh@kernel.org>
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