kernel/ARM-cpufreq-support-for-Raspberry-Pi.patch

From ba60a01e02086b0a242cf5ea3c59419108ada40b Mon Sep 17 00:00:00 2001
From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Date: Tue, 11 Jun 2019 19:58:34 +0200
Subject: [PATCH 1/5] clk: bcm2835: remove pllb

Raspberry Pi's firmware controls this pll, we should use the firmware
interface to access it.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Eric Anholt <eric@anholt.net>
---
 drivers/clk/bcm/clk-bcm2835.c | 28 ++++------------------------
 1 file changed, 4 insertions(+), 24 deletions(-)

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 770bb01f523e..867ae3c20041 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1651,30 +1651,10 @@ static const struct bcm2835_clk_desc clk_desc_array[] = {
 		.fixed_divider = 1,
 		.flags = CLK_SET_RATE_PARENT),
 
-	/* PLLB is used for the ARM's clock. */
-	[BCM2835_PLLB]		= REGISTER_PLL(
-		.name = "pllb",
-		.cm_ctrl_reg = CM_PLLB,
-		.a2w_ctrl_reg = A2W_PLLB_CTRL,
-		.frac_reg = A2W_PLLB_FRAC,
-		.ana_reg_base = A2W_PLLB_ANA0,
-		.reference_enable_mask = A2W_XOSC_CTRL_PLLB_ENABLE,
-		.lock_mask = CM_LOCK_FLOCKB,
-
-		.ana = &bcm2835_ana_default,
-
-		.min_rate = 600000000u,
-		.max_rate = 3000000000u,
-		.max_fb_rate = BCM2835_MAX_FB_RATE),
-	[BCM2835_PLLB_ARM]	= REGISTER_PLL_DIV(
-		.name = "pllb_arm",
-		.source_pll = "pllb",
-		.cm_reg = CM_PLLB,
-		.a2w_reg = A2W_PLLB_ARM,
-		.load_mask = CM_PLLB_LOADARM,
-		.hold_mask = CM_PLLB_HOLDARM,
-		.fixed_divider = 1,
-		.flags = CLK_SET_RATE_PARENT),
+	/*
+	 * PLLB is used for the ARM's clock. Controlled by firmware, see
+	 * clk-raspberrypi.c.
+	 */
 
 	/*
 	 * PLLC is the core PLL, used to drive the core VPU clock.
-- 
2.21.0

From 64482a97a0a2f14ebdbfe80a8eb0e063d293807b Mon Sep 17 00:00:00 2001
From: Peter Robinson <pbrobinson@gmail.com>
Date: Wed, 12 Jun 2019 17:23:12 +0100
Subject: [PATCH 2/5] clk: bcm283x: add driver interfacing with Raspberry Pi's
 firmware

Raspberry Pi's firmware offers an interface though which update it's
clock's frequencies. This is specially useful in order to change the CPU
clock (pllb_arm) which is 'owned' by the firmware and we're unable to
scale using the register interface provided by clk-bcm2835.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
---
 drivers/clk/bcm/Kconfig           |   7 +
 drivers/clk/bcm/Makefile          |   1 +
 drivers/clk/bcm/clk-raspberrypi.c | 300 ++++++++++++++++++++++++++++++
 3 files changed, 308 insertions(+)
 create mode 100644 drivers/clk/bcm/clk-raspberrypi.c

diff --git a/drivers/clk/bcm/Kconfig b/drivers/clk/bcm/Kconfig
index 29ee7b776cd4..a4a2775d65e1 100644
--- a/drivers/clk/bcm/Kconfig
+++ b/drivers/clk/bcm/Kconfig
@@ -64,3 +64,10 @@ config CLK_BCM_SR
 	default ARCH_BCM_IPROC
 	help
 	  Enable common clock framework support for the Broadcom Stingray SoC
+
+config CLK_RASPBERRYPI
+	tristate "Raspberry Pi firmware based clock support"
+	depends on RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE)
+	help
+	  Enable common clock framework support for Raspberry Pi's firmware
+	  dependent clocks
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index 002661d39128..eb7159099d82 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_CLK_BCM_KONA)	+= clk-bcm21664.o
 obj-$(CONFIG_COMMON_CLK_IPROC)	+= clk-iproc-armpll.o clk-iproc-pll.o clk-iproc-asiu.o
 obj-$(CONFIG_ARCH_BCM2835)	+= clk-bcm2835.o
 obj-$(CONFIG_ARCH_BCM2835)	+= clk-bcm2835-aux.o
+obj-$(CONFIG_CLK_RASPBERRYPI)	+= clk-raspberrypi.o
 obj-$(CONFIG_ARCH_BCM_53573)	+= clk-bcm53573-ilp.o
 obj-$(CONFIG_CLK_BCM_CYGNUS)	+= clk-cygnus.o
 obj-$(CONFIG_CLK_BCM_HR2)	+= clk-hr2.o
diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
new file mode 100644
index 000000000000..467933767106
--- /dev/null
+++ b/drivers/clk/bcm/clk-raspberrypi.c
@@ -0,0 +1,300 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Raspberry Pi driver for firmware controlled clocks
+ *
+ * Even though clk-bcm2835 provides an interface to the hardware registers for
+ * the system clocks we've had to factor out 'pllb' as the firmware 'owns' it.
+ * We're not allowed to change it directly as we might race with the
+ * over-temperature and under-voltage protections provided by the firmware.
+ *
+ * Copyright (C) 2019 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
+ */
+
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define RPI_FIRMWARE_ARM_CLK_ID		0x000000003
+
+#define RPI_FIRMWARE_STATE_ENABLE_BIT	BIT(0)
+#define RPI_FIRMWARE_STATE_WAIT_BIT	BIT(1)
+
+/*
+ * Even though the firmware interface alters 'pllb' the frequencies are
+ * provided as per 'pllb_arm'. We need to scale before passing them trough.
+ */
+#define RPI_FIRMWARE_PLLB_ARM_DIV_RATE	2
+
+#define A2W_PLL_FRAC_BITS		20
+
+struct raspberrypi_clk {
+	struct device *dev;
+	struct rpi_firmware *firmware;
+
+	unsigned long min_rate;
+	unsigned long max_rate;
+
+	struct clk_hw pllb;
+	struct clk_hw *pllb_arm;
+	struct clk_lookup *pllb_arm_lookup;
+};
+
+/*
+ * Structure of the message passed to Raspberry Pi's firmware in order to
+ * change clock rates. The 'disable_turbo' option is only available to the ARM
+ * clock (pllb) which we enable by default as turbo mode will alter multiple
+ * clocks at once.
+ *
+ * Even though we're able to access the clock registers directly we're bound to
+ * use the firmware interface as the firmware ultimately takes care of
+ * mitigating overheating/undervoltage situations and we would be changing
+ * frequencies behind his back.
+ *
+ * For more information on the firmware interface check:
+ * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
+ */
+struct raspberrypi_firmware_prop {
+	__le32 id;
+	__le32 val;
+	__le32 disable_turbo;
+} __packed;
+
+static int raspberrypi_clock_property(struct rpi_firmware *firmware, u32 tag,
+				      u32 clk, u32 *val)
+{
+	struct raspberrypi_firmware_prop msg = {
+		.id = clk,
+		.val = *val,
+		.disable_turbo = 1,
+	};
+	int ret;
+
+	ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
+	if (ret)
+		return ret;
+
+	*val = msg.val;
+
+	return 0;
+}
+
+static int raspberrypi_fw_pll_is_on(struct clk_hw *hw)
+{
+	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
+						   pllb);
+	u32 val = 0;
+	int ret;
+
+	ret = raspberrypi_clock_property(rpi->firmware,
+					 RPI_FIRMWARE_GET_CLOCK_STATE,
+					 RPI_FIRMWARE_ARM_CLK_ID, &val);
+	if (ret)
+		return 0;
+
+	return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
+}
+
+
+static unsigned long raspberrypi_fw_pll_get_rate(struct clk_hw *hw,
+						 unsigned long parent_rate)
+{
+	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
+						   pllb);
+	u32 val = 0;
+	int ret;
+
+	ret = raspberrypi_clock_property(rpi->firmware,
+					 RPI_FIRMWARE_GET_CLOCK_RATE,
+					 RPI_FIRMWARE_ARM_CLK_ID,
+					 &val);
+	if (ret)
+		return ret;
+
+	return val * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
+}
+
+static int raspberrypi_fw_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+				       unsigned long parent_rate)
+{
+	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
+						   pllb);
+	u32 new_rate = rate / RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
+	int ret;
+
+	ret = raspberrypi_clock_property(rpi->firmware,
+					 RPI_FIRMWARE_SET_CLOCK_RATE,
+					 RPI_FIRMWARE_ARM_CLK_ID,
+					 &new_rate);
+	if (ret)
+		dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d",
+				    clk_hw_get_name(hw), ret);
+
+	return ret;
+}
+
+/*
+ * Sadly there is no firmware rate rounding interface. We borrowed it from
+ * clk-bcm2835.
+ */
+static int raspberrypi_pll_determine_rate(struct clk_hw *hw,
+					  struct clk_rate_request *req)
+{
+	struct raspberrypi_clk *rpi = container_of(hw, struct raspberrypi_clk,
+						   pllb);
+	u64 div, final_rate;
+	u32 ndiv, fdiv;
+
+	/* We can't use req->rate directly as it would overflow */
+	final_rate = clamp(req->rate, rpi->min_rate, rpi->max_rate);
+
+	div = (u64)final_rate << A2W_PLL_FRAC_BITS;
+	do_div(div, req->best_parent_rate);
+
+	ndiv = div >> A2W_PLL_FRAC_BITS;
+	fdiv = div & ((1 << A2W_PLL_FRAC_BITS) - 1);
+
+	final_rate = ((u64)req->best_parent_rate *
+					((ndiv << A2W_PLL_FRAC_BITS) + fdiv));
+
+	req->rate = final_rate >> A2W_PLL_FRAC_BITS;
+
+	return 0;
+}
+
+static const struct clk_ops raspberrypi_firmware_pll_clk_ops = {
+	.is_prepared = raspberrypi_fw_pll_is_on,
+	.recalc_rate = raspberrypi_fw_pll_get_rate,
+	.set_rate = raspberrypi_fw_pll_set_rate,
+	.determine_rate = raspberrypi_pll_determine_rate,
+};
+
+static int raspberrypi_register_pllb(struct raspberrypi_clk *rpi)
+{
+	u32 min_rate = 0, max_rate = 0;
+	struct clk_init_data init;
+	int ret;
+
+	memset(&init, 0, sizeof(init));
+
+	/* All of the PLLs derive from the external oscillator. */
+	init.parent_names = (const char *[]){ "osc" };
+	init.num_parents = 1;
+	init.name = "pllb";
+	init.ops = &raspberrypi_firmware_pll_clk_ops;
+	init.flags = CLK_GET_RATE_NOCACHE | CLK_IGNORE_UNUSED;
+
+	/* Get min & max rates set by the firmware */
+	ret = raspberrypi_clock_property(rpi->firmware,
+					 RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
+					 RPI_FIRMWARE_ARM_CLK_ID,
+					 &min_rate);
+	if (ret) {
+		dev_err(rpi->dev, "Failed to get %s min freq: %d\n",
+			init.name, ret);
+		return ret;
+	}
+
+	ret = raspberrypi_clock_property(rpi->firmware,
+					 RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
+					 RPI_FIRMWARE_ARM_CLK_ID,
+					 &max_rate);
+	if (ret) {
+		dev_err(rpi->dev, "Failed to get %s max freq: %d\n",
+			init.name, ret);
+		return ret;
+	}
+
+	if (!min_rate || !max_rate) {
+		dev_err(rpi->dev, "Unexpected frequency range: min %u, max %u\n",
+			min_rate, max_rate);
+		return -EINVAL;
+	}
+
+	dev_info(rpi->dev, "CPU frequency range: min %u, max %u\n",
+		 min_rate, max_rate);
+
+	rpi->min_rate = min_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
+	rpi->max_rate = max_rate * RPI_FIRMWARE_PLLB_ARM_DIV_RATE;
+
+	rpi->pllb.init = &init;
+
+	return devm_clk_hw_register(rpi->dev, &rpi->pllb);
+}
+
+static int raspberrypi_register_pllb_arm(struct raspberrypi_clk *rpi)
+{
+	rpi->pllb_arm = clk_hw_register_fixed_factor(rpi->dev,
+				"pllb_arm", "pllb",
+				CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE,
+				1, 2);
+	if (IS_ERR(rpi->pllb_arm)) {
+		dev_err(rpi->dev, "Failed to initialize pllb_arm\n");
+		return PTR_ERR(rpi->pllb_arm);
+	}
+
+	rpi->pllb_arm_lookup = clkdev_hw_create(rpi->pllb_arm, NULL, "cpu0");
+	if (!rpi->pllb_arm_lookup) {
+		dev_err(rpi->dev, "Failed to initialize pllb_arm_lookup\n");
+		clk_hw_unregister_fixed_factor(rpi->pllb_arm);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int raspberrypi_clk_probe(struct platform_device *pdev)
+{
+	struct device_node *firmware_node;
+	struct device *dev = &pdev->dev;
+	struct rpi_firmware *firmware;
+	struct raspberrypi_clk *rpi;
+	int ret;
+
+	firmware_node = of_find_compatible_node(NULL, NULL,
+					"raspberrypi,bcm2835-firmware");
+	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;
+
+	rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
+	if (!rpi)
+		return -ENOMEM;
+
+	rpi->dev = dev;
+	rpi->firmware = firmware;
+
+	ret = raspberrypi_register_pllb(rpi);
+	if (ret) {
+		dev_err(dev, "Failed to initialize pllb, %d\n", ret);
+		return ret;
+	}
+
+	ret = raspberrypi_register_pllb_arm(rpi);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static struct platform_driver raspberrypi_clk_driver = {
+	.driver = {
+		.name = "raspberrypi-clk",
+	},
+	.probe          = raspberrypi_clk_probe,
+};
+module_platform_driver(raspberrypi_clk_driver);
+
+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
+MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:raspberrypi-clk");
-- 
2.21.0

From e750e62addb9ee00f47ab4a73c0645d44172ab12 Mon Sep 17 00:00:00 2001
From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Date: Tue, 11 Jun 2019 19:58:38 +0200
Subject: [PATCH 3/5] firmware: raspberrypi: register clk device

Since clk-raspberrypi is tied to the VC4 firmware instead of particular
hardware it's registration should be performed by the firmware driver.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Eric Anholt <eric@anholt.net>
---
 drivers/firmware/raspberrypi.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index 61be15d9df7d..da26a584dca0 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -20,6 +20,7 @@
 #define MBOX_CHAN_PROPERTY		8
 
 static struct platform_device *rpi_hwmon;
+static struct platform_device *rpi_clk;
 
 struct rpi_firmware {
 	struct mbox_client cl;
@@ -207,6 +208,12 @@ rpi_register_hwmon_driver(struct device *dev, struct rpi_firmware *fw)
 						  -1, NULL, 0);
 }
 
+static void rpi_register_clk_driver(struct device *dev)
+{
+	rpi_clk = platform_device_register_data(dev, "raspberrypi-clk",
+						-1, NULL, 0);
+}
+
 static int rpi_firmware_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -234,6 +241,7 @@ static int rpi_firmware_probe(struct platform_device *pdev)
 
 	rpi_firmware_print_firmware_revision(fw);
 	rpi_register_hwmon_driver(dev, fw);
+	rpi_register_clk_driver(dev);
 
 	return 0;
 }
@@ -254,6 +262,8 @@ static int rpi_firmware_remove(struct platform_device *pdev)
 
 	platform_device_unregister(rpi_hwmon);
 	rpi_hwmon = NULL;
+	platform_device_unregister(rpi_clk);
+	rpi_clk = NULL;
 	mbox_free_channel(fw->chan);
 
 	return 0;
-- 
2.21.0

From af32d83d10976ff357c56adba79fa3cb06e1c32d Mon Sep 17 00:00:00 2001
From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Date: Tue, 11 Jun 2019 19:58:42 +0200
Subject: [PATCH 5/5] clk: raspberrypi: register platform device for
 raspberrypi-cpufreq

As 'clk-raspberrypi' depends on RPi's firmware interface, which might be
configured as a module, the cpu clock might not be available for the
cpufreq driver during it's init process. So we register the
'raspberrypi-cpufreq' platform device after the probe sequence succeeds.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Acked-by: Eric Anholt <eric@anholt.net>
---
 drivers/clk/bcm/clk-raspberrypi.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/clk/bcm/clk-raspberrypi.c b/drivers/clk/bcm/clk-raspberrypi.c
index 467933767106..7f9b001f8d70 100644
--- a/drivers/clk/bcm/clk-raspberrypi.c
+++ b/drivers/clk/bcm/clk-raspberrypi.c
@@ -34,6 +34,7 @@
 struct raspberrypi_clk {
 	struct device *dev;
 	struct rpi_firmware *firmware;
+	struct platform_device *cpufreq;
 
 	unsigned long min_rate;
 	unsigned long max_rate;
@@ -272,6 +273,7 @@ static int raspberrypi_clk_probe(struct platform_device *pdev)
 
 	rpi->dev = dev;
 	rpi->firmware = firmware;
+	platform_set_drvdata(pdev, rpi);
 
 	ret = raspberrypi_register_pllb(rpi);
 	if (ret) {
@@ -283,6 +285,18 @@ static int raspberrypi_clk_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
+						     -1, NULL, 0);
+
+	return 0;
+}
+
+static int raspberrypi_clk_remove(struct platform_device *pdev)
+{
+	struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);
+
+	platform_device_unregister(rpi->cpufreq);
+
 	return 0;
 }
 
@@ -291,6 +305,7 @@ static struct platform_driver raspberrypi_clk_driver = {
 		.name = "raspberrypi-clk",
 	},
 	.probe          = raspberrypi_clk_probe,
+	.remove		= raspberrypi_clk_remove,
 };
 module_platform_driver(raspberrypi_clk_driver);
 
-- 
2.21.0