[PATCH v4 0/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[PATCH v4 0/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Markus Mayer]

From: Markus Mayer <mmayer@broadcom.com>

This CPUfreq driver provides basic frequency scaling for older Broadcom
STB SoCs that do not use AVS firmware with DVFS support. There is no
support for voltage scaling.

v3 of this patch can be found here: https://lkml.org/lkml/2016/11/22/747

Changes since v3:
  - added binding document
  - got rid of calls to __clk_lookup(), using devm_clk_get() instead
  - re-worked clock lookup code a bit, along with switching to devm_clk_get()
  - get_frequencies() became a void function, removing the need for some
    error checking
  - fixed CONFIG_ARM_BRCM_AVS_CPUFREQ typo
  - fixed MODULE_DEVICE_TABLE declaration

Markus Mayer (2):
  dt-bindings: brcm: clocks: add binding for brcmstb-cpu-clk-div
  cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

 .../bindings/clock/brcm,brcmstb-cpu-clk-div.txt    |  83 +++++
 MAINTAINERS                                        |   1 +
 drivers/cpufreq/Kconfig.arm                        |  12 +
 drivers/cpufreq/Makefile                           |   1 +
 drivers/cpufreq/brcmstb-cpufreq.c                  | 377 +++++++++++++++++++++
 5 files changed, 474 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
 create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c

-- 
2.7.4

[PATCH v4 0/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Markus Mayer]

From: Markus Mayer <mmayer@broadcom.com>

This CPUfreq driver provides basic frequency scaling for older Broadcom
STB SoCs that do not use AVS firmware with DVFS support. There is no
support for voltage scaling.

v3 of this patch can be found here: https://lkml.org/lkml/2016/11/22/747

Changes since v3:
  - added binding document
  - got rid of calls to __clk_lookup(), using devm_clk_get() instead
  - re-worked clock lookup code a bit, along with switching to devm_clk_get()
  - get_frequencies() became a void function, removing the need for some
    error checking
  - fixed CONFIG_ARM_BRCM_AVS_CPUFREQ typo
  - fixed MODULE_DEVICE_TABLE declaration

Markus Mayer (2):
  dt-bindings: brcm: clocks: add binding for brcmstb-cpu-clk-div
  cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

 .../bindings/clock/brcm,brcmstb-cpu-clk-div.txt    |  83 +++++
 MAINTAINERS                                        |   1 +
 drivers/cpufreq/Kconfig.arm                        |  12 +
 drivers/cpufreq/Makefile                           |   1 +
 drivers/cpufreq/brcmstb-cpufreq.c                  | 377 +++++++++++++++++++++
 5 files changed, 474 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
 create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c

-- 
2.7.4

[PATCH v4 1/2] dt-bindings: brcm: clocks: add binding for brcmstb-cpu-clk-div

[Markus Mayer]

From: Markus Mayer <mmayer@broadcom.com>

Add binding document for brcm,brcmstb-cpu-clk-div.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
 .../bindings/clock/brcm,brcmstb-cpu-clk-div.txt    | 83 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 2 files changed, 84 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt

diff --git a/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
new file mode 100644
index 0000000..3bc99c5
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
@@ -0,0 +1,83 @@
+The CPU divider node serves as the sole clock for the CPU complex. It supports
+power-of-2 clock division, with a divider of "1" as the default highest-speed
+setting.
+
+Required properties:
+- compatible: shall be "brcm,brcmstb-cpu-clk-div"
+- reg: address and width of the divider configuration register
+- #clock-cells: shall be set to 0
+- clocks: phandle of clock provider which provides the source clock
+          (this would typically be a "fixed-clock" type PLL)
+- div-table: list of (raw_value,divider) ordered pairs that correspond to the
+             allowed clock divider settings
+- div-shift-width: least-significant bit position and width of divider value
+
+Optional properties:
+- clocks: additional clocks can be specified if needed
+- clock-names: clocks can be named, so they can be looked up
+
+Example:
+	sw_scb: sw_scb {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <432000000>;
+	};
+
+	fixed0: fixed0 {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <54000000>;
+	};
+
+	cpu_pdiv: cpu_pdiv@f04e0008 {
+		compatible = "divider-clock";
+		#clock-cells = <0>;
+		reg = <0xf04e0008 0x4>;
+		bit-shift = <10>;
+		bit-mask = <0xf>;
+		index-starts-at-one;
+		clocks = <&fixed0>;
+		clock-names = "fixed0";
+	};
+
+	cpu_ndiv_int: cpu_ndiv_int {
+		compatible = "fixed-factor-clock";
+		#clock-cells = <0>;
+		clock-div = <1>;
+		clock-mult = <167>;
+		clocks = <&cpu_pdiv>;
+		clock-names = "cpu_pdiv";
+	};
+
+	cpu_mdiv_ch0: cpu_mdiv_ch0@f04e0000 {
+		compatible = "divider-clock";
+		#clock-cells = <0>;
+		reg = <0xf04e0000 0x4>;
+		bit-shift = <1>;
+		bit-mask = <0xff>;
+		index-starts-at-one;
+		clocks = <&cpu_ndiv_int>;
+		clock-names = "cpu_ndiv_int";
+	};
+
+	cpupll: cpupll@0 {
+		#clock-cells = <0>;
+		clock-frequency = <1503000000>;
+		compatible = "fixed-clock";
+	};
+
+	cpuclkdiv: cpu-clk-div@0 {
+		#clock-cells = <0>;
+		clock-names = "cpupll",
+			"cpu_mdiv_ch0",
+			"cpu_ndiv_int",
+			"sw_scb";
+		clocks = <&cpupll,
+			&cpu_mdiv_ch0,
+			&cpu_ndiv_int,
+			&sw_scb>;
+		compatible = "brcm,brcmstb-cpu-clk-div";
+		reg = <0xf03e257c 0x4>;
+		div-table = <0x00 1>;
+		div-shift-width = <0 5>;
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index f6eb97b..5473b31 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2786,6 +2786,7 @@ M:	bcm-kernel-feedback-list@broadcom.com
 L:	linux-pm@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/cpufreq/brcm,stb-avs-cpu-freq.txt
+F:	Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
 F:	drivers/cpufreq/brcmstb*
 
 BROADCOM SPECIFIC AMBA DRIVER (BCMA)
-- 
2.7.4

[PATCH v4 1/2] dt-bindings: brcm: clocks: add binding for brcmstb-cpu-clk-div

[Markus Mayer]

From: Markus Mayer <mmayer@broadcom.com>

Add binding document for brcm,brcmstb-cpu-clk-div.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
 .../bindings/clock/brcm,brcmstb-cpu-clk-div.txt    | 83 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 2 files changed, 84 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt

diff --git a/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
new file mode 100644
index 0000000..3bc99c5
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
@@ -0,0 +1,83 @@
+The CPU divider node serves as the sole clock for the CPU complex. It supports
+power-of-2 clock division, with a divider of "1" as the default highest-speed
+setting.
+
+Required properties:
+- compatible: shall be "brcm,brcmstb-cpu-clk-div"
+- reg: address and width of the divider configuration register
+- #clock-cells: shall be set to 0
+- clocks: phandle of clock provider which provides the source clock
+          (this would typically be a "fixed-clock" type PLL)
+- div-table: list of (raw_value,divider) ordered pairs that correspond to the
+             allowed clock divider settings
+- div-shift-width: least-significant bit position and width of divider value
+
+Optional properties:
+- clocks: additional clocks can be specified if needed
+- clock-names: clocks can be named, so they can be looked up
+
+Example:
+	sw_scb: sw_scb {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <432000000>;
+	};
+
+	fixed0: fixed0 {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <54000000>;
+	};
+
+	cpu_pdiv: cpu_pdiv@f04e0008 {
+		compatible = "divider-clock";
+		#clock-cells = <0>;
+		reg = <0xf04e0008 0x4>;
+		bit-shift = <10>;
+		bit-mask = <0xf>;
+		index-starts-at-one;
+		clocks = <&fixed0>;
+		clock-names = "fixed0";
+	};
+
+	cpu_ndiv_int: cpu_ndiv_int {
+		compatible = "fixed-factor-clock";
+		#clock-cells = <0>;
+		clock-div = <1>;
+		clock-mult = <167>;
+		clocks = <&cpu_pdiv>;
+		clock-names = "cpu_pdiv";
+	};
+
+	cpu_mdiv_ch0: cpu_mdiv_ch0@f04e0000 {
+		compatible = "divider-clock";
+		#clock-cells = <0>;
+		reg = <0xf04e0000 0x4>;
+		bit-shift = <1>;
+		bit-mask = <0xff>;
+		index-starts-at-one;
+		clocks = <&cpu_ndiv_int>;
+		clock-names = "cpu_ndiv_int";
+	};
+
+	cpupll: cpupll@0 {
+		#clock-cells = <0>;
+		clock-frequency = <1503000000>;
+		compatible = "fixed-clock";
+	};
+
+	cpuclkdiv: cpu-clk-div@0 {
+		#clock-cells = <0>;
+		clock-names = "cpupll",
+			"cpu_mdiv_ch0",
+			"cpu_ndiv_int",
+			"sw_scb";
+		clocks = <&cpupll,
+			&cpu_mdiv_ch0,
+			&cpu_ndiv_int,
+			&sw_scb>;
+		compatible = "brcm,brcmstb-cpu-clk-div";
+		reg = <0xf03e257c 0x4>;
+		div-table = <0x00 1>;
+		div-shift-width = <0 5>;
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index f6eb97b..5473b31 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2786,6 +2786,7 @@ M:	bcm-kernel-feedback-list@broadcom.com
 L:	linux-pm@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/cpufreq/brcm,stb-avs-cpu-freq.txt
+F:	Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
 F:	drivers/cpufreq/brcmstb*
 
 BROADCOM SPECIFIC AMBA DRIVER (BCMA)
-- 
2.7.4

[PATCH v4 1/2] dt-bindings: brcm: clocks: add binding for brcmstb-cpu-clk-div

[Markus Mayer]

From: Markus Mayer <mmayer@broadcom.com>

Add binding document for brcm,brcmstb-cpu-clk-div.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
 .../bindings/clock/brcm,brcmstb-cpu-clk-div.txt    | 83 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 2 files changed, 84 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt

diff --git a/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
new file mode 100644
index 0000000..3bc99c5
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
@@ -0,0 +1,83 @@
+The CPU divider node serves as the sole clock for the CPU complex. It supports
+power-of-2 clock division, with a divider of "1" as the default highest-speed
+setting.
+
+Required properties:
+- compatible: shall be "brcm,brcmstb-cpu-clk-div"
+- reg: address and width of the divider configuration register
+- #clock-cells: shall be set to 0
+- clocks: phandle of clock provider which provides the source clock
+          (this would typically be a "fixed-clock" type PLL)
+- div-table: list of (raw_value,divider) ordered pairs that correspond to the
+             allowed clock divider settings
+- div-shift-width: least-significant bit position and width of divider value
+
+Optional properties:
+- clocks: additional clocks can be specified if needed
+- clock-names: clocks can be named, so they can be looked up
+
+Example:
+	sw_scb: sw_scb {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <432000000>;
+	};
+
+	fixed0: fixed0 {
+		compatible = "fixed-clock";
+		#clock-cells = <0>;
+		clock-frequency = <54000000>;
+	};
+
+	cpu_pdiv: cpu_pdiv at f04e0008 {
+		compatible = "divider-clock";
+		#clock-cells = <0>;
+		reg = <0xf04e0008 0x4>;
+		bit-shift = <10>;
+		bit-mask = <0xf>;
+		index-starts-at-one;
+		clocks = <&fixed0>;
+		clock-names = "fixed0";
+	};
+
+	cpu_ndiv_int: cpu_ndiv_int {
+		compatible = "fixed-factor-clock";
+		#clock-cells = <0>;
+		clock-div = <1>;
+		clock-mult = <167>;
+		clocks = <&cpu_pdiv>;
+		clock-names = "cpu_pdiv";
+	};
+
+	cpu_mdiv_ch0: cpu_mdiv_ch0 at f04e0000 {
+		compatible = "divider-clock";
+		#clock-cells = <0>;
+		reg = <0xf04e0000 0x4>;
+		bit-shift = <1>;
+		bit-mask = <0xff>;
+		index-starts-at-one;
+		clocks = <&cpu_ndiv_int>;
+		clock-names = "cpu_ndiv_int";
+	};
+
+	cpupll: cpupll at 0 {
+		#clock-cells = <0>;
+		clock-frequency = <1503000000>;
+		compatible = "fixed-clock";
+	};
+
+	cpuclkdiv: cpu-clk-div at 0 {
+		#clock-cells = <0>;
+		clock-names = "cpupll",
+			"cpu_mdiv_ch0",
+			"cpu_ndiv_int",
+			"sw_scb";
+		clocks = <&cpupll,
+			&cpu_mdiv_ch0,
+			&cpu_ndiv_int,
+			&sw_scb>;
+		compatible = "brcm,brcmstb-cpu-clk-div";
+		reg = <0xf03e257c 0x4>;
+		div-table = <0x00 1>;
+		div-shift-width = <0 5>;
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index f6eb97b..5473b31 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2786,6 +2786,7 @@ M:	bcm-kernel-feedback-list at broadcom.com
 L:	linux-pm at vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/cpufreq/brcm,stb-avs-cpu-freq.txt
+F:	Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
 F:	drivers/cpufreq/brcmstb*
 
 BROADCOM SPECIFIC AMBA DRIVER (BCMA)
-- 
2.7.4

[PATCH v4 2/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Markus Mayer]

From: Markus Mayer <mmayer@broadcom.com>

This CPUfreq driver provides basic frequency scaling for older Broadcom
STB SoCs that do not use AVS firmware with DVFS support. There is no
support for voltage scaling.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
 drivers/cpufreq/Kconfig.arm       |  12 ++
 drivers/cpufreq/Makefile          |   1 +
 drivers/cpufreq/brcmstb-cpufreq.c | 377 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 390 insertions(+)
 create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 920c469..36422af 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -33,6 +33,18 @@ config ARM_BRCMSTB_AVS_CPUFREQ_DEBUG
 
 	  If in doubt, say N.
 
+config ARM_BRCMSTB_CPUFREQ
+	tristate "Broadcom STB CPUfreq driver"
+	depends on ARCH_BRCMSTB || COMPILE_TEST
+	default y
+	help
+	  Some Broadcom SoCs offer multiple operating frequencies that CPUfreq
+	  can take advantage of to improve energy efficiency.
+
+	  Say Y, if you have a supported Broadcom SoC. If your Broadcom SoC
+	  has AVS firmware with support for frequency and voltage scaling,
+	  say N here and enable ARM_BRCMSTB_AVS_CPUFREQ instead.
+
 config ARM_DT_BL_CPUFREQ
 	tristate "Generic probing via DT for ARM big LITTLE CPUfreq driver"
 	depends on ARM_BIG_LITTLE_CPUFREQ && OF
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 1e46c39..23700aa 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_ARM_BIG_LITTLE_CPUFREQ)	+= arm_big_little.o
 obj-$(CONFIG_ARM_DT_BL_CPUFREQ)		+= arm_big_little_dt.o
 
 obj-$(CONFIG_ARM_BRCMSTB_AVS_CPUFREQ)	+= brcmstb-avs-cpufreq.o
+obj-$(CONFIG_ARM_BRCMSTB_CPUFREQ)	+= brcmstb-cpufreq.o
 obj-$(CONFIG_ARCH_DAVINCI)		+= davinci-cpufreq.o
 obj-$(CONFIG_UX500_SOC_DB8500)		+= dbx500-cpufreq.o
 obj-$(CONFIG_ARM_EXYNOS5440_CPUFREQ)	+= exynos5440-cpufreq.o
diff --git a/drivers/cpufreq/brcmstb-cpufreq.c b/drivers/cpufreq/brcmstb-cpufreq.c
new file mode 100644
index 0000000..80ac1ae
--- /dev/null
+++ b/drivers/cpufreq/brcmstb-cpufreq.c
@@ -0,0 +1,377 @@
+/*
+ * CPU frequency scaling for Broadcom set top box SoCs
+ *
+ * Copyright (c) 2016 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/cpufreq.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+#define BRCMSTB_CPUFREQ_PREFIX	"brcmstb"
+#define BRCMSTB_CPUFREQ_NAME	BRCMSTB_CPUFREQ_PREFIX "-cpufreq"
+
+/* We search for these compatible strings. */
+#define BRCMSTB_DT_CPU_CLK_CTRL	"brcm,brcmstb-cpu-clk-div"
+#define BRCMSTB_DT_MEMC_DDR	"brcm,brcmstb-memc-ddr"
+#define BRCM_AVS_CPU_DATA	"brcm,avs-cpu-data-mem"
+
+/*
+ * We also need a few clocks in device tree. They are referenced in the
+ * brcm,brcmstb-cpu-clk-div node in device tree, so we can look them up.
+ */
+#define BRCMSTB_CLK_MDIV_CH0	"cpu_mdiv_ch0"
+#define BRCMSTB_CLK_NDIV_INT	"cpu_ndiv_int"
+#define BRCMSTB_CLK_SW_SCB	"sw_scb"
+
+#define BRCMSTB_TBL_SAFE_MODE	BIT(0)
+#define BRCMSTB_REG_SAFE_MODE	BIT(4)
+
+#define TRANSITION_LATENCY	(25 * 1000)	/* 25 us */
+
+/* This is as low as we'll go in the frequency table. */
+#define MIN_CPU_FREQ		(100 * 1000)	/* in kHz */
+
+struct private_data {
+	void __iomem *cpu_clk_ctrl_reg;
+	struct clk *mdiv_clk;
+	struct clk *ndiv_clk;
+	struct clk *sw_scb_clk;
+	struct device *dev;
+};
+
+/* Count the active memory controllers in the system. */
+static int count_memory_controllers(void)
+{
+	struct device_node *np = NULL;
+	int i = 0;
+
+	do {
+		np = of_find_compatible_node(np, NULL, BRCMSTB_DT_MEMC_DDR);
+		if (of_device_is_available(np))
+			i++;
+		of_node_put(np);
+	} while (np);
+
+	return i;
+}
+
+static void get_frequencies(const struct cpufreq_policy *policy,
+			   unsigned int *vco_freq, unsigned int *cpu_freq,
+			   unsigned int *scb_freq)
+{
+	struct private_data *priv = policy->driver_data;
+
+	/* return frequencies in kHz */
+	*vco_freq = clk_get_rate(priv->ndiv_clk) / 1000;
+	*cpu_freq = clk_get_rate(priv->mdiv_clk) / 1000;
+	*scb_freq = clk_get_rate(priv->sw_scb_clk) / 1000;
+}
+
+/*
+ * Safe mode: When set, the CPU's bus unit is being throttled. This is done to
+ * avoid buffer overflows when the CPU-to-bus-clock ratio is low.
+ *
+ * The formula as to what constitutes a low CPU-to-bus-clock ratio takes into
+ * account the number of memory controllers active in the system and the SCB
+ * frequency. More memory controllers means safe mode is required starting at
+ * higher frequencies.
+ *
+ * For 1 memory controller, cpu_freq/scb_freq must be greater than or equal to
+ * 2 to not require safe mode.
+ *
+ * For 2 or 3 memory controllers, cpu_freq/scb_freq must be greater than or
+ * equal 3 to not require safe mode.
+ */
+
+static int freq_requires_safe_mode(unsigned int cpu_freq, unsigned int scb_freq,
+				   int num_memc)
+{
+	unsigned int safe_ratio;
+
+	switch (num_memc) {
+	case 1:
+		safe_ratio = 2;
+		break;
+	case 2:
+	case 3:
+		safe_ratio = 3;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ((cpu_freq / scb_freq) < safe_ratio);
+}
+
+static struct cpufreq_frequency_table *
+brcmstb_get_freq_table(const struct cpufreq_policy *policy)
+{
+	unsigned int cpu_freq, vco_freq, scb_freq, mdiv, init_mdiv, f;
+	struct cpufreq_frequency_table *table;
+	struct private_data *priv;
+	int num_memc, ret;
+	unsigned int i = 0;
+
+	priv = policy->driver_data;
+	num_memc = count_memory_controllers();
+	get_frequencies(policy, &vco_freq, &cpu_freq, &scb_freq);
+
+	/* Calculate the initial mdiv value. We'll increment mdiv from here. */
+	init_mdiv = vco_freq / cpu_freq;
+
+	/* Count how many frequencies we'll offer. */
+	f = cpu_freq;
+	for (mdiv = init_mdiv; f >= MIN_CPU_FREQ; mdiv++, f = vco_freq / mdiv) {
+		/* We only want to use "whole" MHz. */
+		if ((f % 1000) == 0)
+			i++;
+	}
+
+	table = devm_kzalloc(priv->dev, (i + 1) * sizeof(*table), GFP_KERNEL);
+	if (!table)
+		return ERR_PTR(-ENOMEM);
+
+	/* Now, fill the table. */
+	f = cpu_freq;
+	i = 0;
+	for (mdiv = init_mdiv; f >= MIN_CPU_FREQ; mdiv++, f = vco_freq / mdiv) {
+		if ((f % 1000) == 0) {
+			table[i].frequency = f;
+			ret = freq_requires_safe_mode(f, scb_freq, num_memc);
+			if (ret < 0)
+				return ERR_PTR(ret);
+			if (ret > 0)
+				table[i].driver_data |= BRCMSTB_TBL_SAFE_MODE;
+			i++;
+		}
+	}
+	table[i].frequency = CPUFREQ_TABLE_END;
+
+	return table;
+}
+
+static int brcmstb_target_index(struct cpufreq_policy *policy,
+				unsigned int index)
+{
+	struct cpufreq_frequency_table *entry;
+	struct private_data *priv;
+	int ret, safe_mode_needed;
+	u32 reg;
+
+	priv = policy->driver_data;
+	entry = &policy->freq_table[index];
+	safe_mode_needed = entry->driver_data & BRCMSTB_TBL_SAFE_MODE;
+
+	reg = readl(priv->cpu_clk_ctrl_reg);
+	if (safe_mode_needed && !(reg & BRCMSTB_REG_SAFE_MODE)) {
+		reg |= BRCMSTB_REG_SAFE_MODE;
+		writel(reg, priv->cpu_clk_ctrl_reg);
+	}
+	ret = clk_set_rate(policy->clk, entry->frequency * 1000);
+	if (!ret && !safe_mode_needed && (reg & BRCMSTB_REG_SAFE_MODE)) {
+		reg &= ~BRCMSTB_REG_SAFE_MODE;
+		writel(reg, priv->cpu_clk_ctrl_reg);
+	}
+
+	return ret;
+}
+
+/*
+ * All initialization code that we only want to execute once goes here. Setup
+ * code that can be re-tried on every core (if it failed before) can go into
+ * brcmstb_cpufreq_init().
+ */
+static int brcmstb_prepare_init(struct platform_device *pdev)
+{
+	struct private_data *priv;
+	struct resource *res;
+	struct device *dev;
+
+	/*
+	 * If the BRCM STB AVS CPUfreq driver is supported, we bail, so that
+	 * the more modern approach implementing DVFS in firmware can be used.
+	 */
+	if (IS_ENABLED(CONFIG_ARM_BRCMSTB_AVS_CPUFREQ)) {
+		struct device_node *np;
+
+		np = of_find_compatible_node(NULL, NULL, BRCM_AVS_CPU_DATA);
+		if (np) {
+			of_node_put(np);
+			return -ENXIO;
+		}
+	}
+
+	dev = &pdev->dev;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->cpu_clk_ctrl_reg = devm_ioremap_resource(dev, res);
+	if (IS_ERR(priv->cpu_clk_ctrl_reg)) {
+		dev_err(dev, "couldn't map DT entry %s\n",
+			BRCMSTB_DT_CPU_CLK_CTRL);
+		return -ENODEV;
+	}
+
+	priv->mdiv_clk = devm_clk_get(dev, BRCMSTB_CLK_MDIV_CH0);
+	priv->ndiv_clk = devm_clk_get(dev, BRCMSTB_CLK_NDIV_INT);
+	priv->sw_scb_clk = devm_clk_get(dev, BRCMSTB_CLK_SW_SCB);
+
+	if (IS_ERR(priv->mdiv_clk))
+		return PTR_ERR(priv->mdiv_clk);
+	if (IS_ERR(priv->ndiv_clk))
+		return PTR_ERR(priv->ndiv_clk);
+	if (IS_ERR(priv->sw_scb_clk))
+		return PTR_ERR(priv->sw_scb_clk);
+
+	priv->dev = dev;
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static int brcmstb_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct cpufreq_frequency_table *freq_table;
+	struct platform_device *pdev;
+	struct private_data *priv;
+	struct device *dev;
+	int ret;
+
+	pdev = cpufreq_get_driver_data();
+	priv = platform_get_drvdata(pdev);
+	dev = &pdev->dev;
+
+	policy->clk = priv->mdiv_clk;
+	policy->driver_data = priv;
+
+	freq_table = brcmstb_get_freq_table(policy);
+	if (IS_ERR(freq_table)) {
+		ret = PTR_ERR(freq_table);
+		dev_err(dev, "Couldn't determine frequency table (%d).\n", ret);
+		if (ret == -EINVAL)
+			dev_emerg(dev,
+				"Invalid number of memory controllers -- %d!\n",
+				count_memory_controllers());
+		return ret;
+	}
+
+	ret = cpufreq_generic_init(policy, freq_table, TRANSITION_LATENCY);
+	if (!ret)
+		dev_info(dev, "registered\n");
+
+	return ret;
+}
+
+/* Shows the number of memory controllers. */
+static ssize_t show_brcmstb_num_memc(struct cpufreq_policy *policy, char *buf)
+{
+	return sprintf(buf, "%u\n", count_memory_controllers());
+}
+
+/* Shows vco_freq, cpu_freq, and scb_freq in kHz. */
+static ssize_t show_brcmstb_freqs(struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int vco_freq, cpu_freq, scb_freq;
+
+	get_frequencies(policy, &vco_freq, &cpu_freq, &scb_freq);
+
+	return sprintf(buf, "%u %u %u\n", vco_freq, cpu_freq, scb_freq);
+}
+
+/* Shows the lowest frequency (in kHz) that can be used without "safe mode". */
+static ssize_t show_brcmstb_safe_freq(struct cpufreq_policy *policy, char *buf)
+{
+	struct cpufreq_frequency_table *entry;
+	unsigned int safe_freq = 0;
+
+	cpufreq_for_each_valid_entry(entry, policy->freq_table) {
+		if (!(entry->driver_data & BRCMSTB_TBL_SAFE_MODE))
+			safe_freq = entry->frequency;
+	}
+
+	return sprintf(buf, "%u\n", safe_freq);
+}
+
+cpufreq_freq_attr_ro(brcmstb_num_memc);
+cpufreq_freq_attr_ro(brcmstb_freqs);
+cpufreq_freq_attr_ro(brcmstb_safe_freq);
+
+static struct freq_attr *brcmstb_cpufreq_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	&brcmstb_num_memc,
+	&brcmstb_freqs,
+	&brcmstb_safe_freq,
+	NULL
+};
+
+static struct cpufreq_driver brcmstb_driver = {
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify		= cpufreq_generic_frequency_table_verify,
+	.target_index	= brcmstb_target_index,
+	.get		= cpufreq_generic_get,
+	.init		= brcmstb_cpufreq_init,
+	.attr		= brcmstb_cpufreq_attr,
+	.name		= BRCMSTB_CPUFREQ_PREFIX,
+};
+
+static int brcmstb_cpufreq_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = brcmstb_prepare_init(pdev);
+	if (ret)
+		return ret;
+
+	brcmstb_driver.driver_data = pdev;
+
+	return cpufreq_register_driver(&brcmstb_driver);
+}
+
+static int brcmstb_cpufreq_remove(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = cpufreq_unregister_driver(&brcmstb_driver);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static const struct of_device_id brcmstb_cpufreq_match[] = {
+	{ .compatible = BRCMSTB_DT_CPU_CLK_CTRL },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, brcmstb_cpufreq_match);
+
+static struct platform_driver brcmstb_cpufreq_platdrv = {
+	.driver = {
+		.name	= BRCMSTB_CPUFREQ_NAME,
+		.of_match_table = brcmstb_cpufreq_match,
+	},
+	.probe		= brcmstb_cpufreq_probe,
+	.remove		= brcmstb_cpufreq_remove,
+};
+module_platform_driver(brcmstb_cpufreq_platdrv);
+
+MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
+MODULE_DESCRIPTION("CPUfreq driver for Broadcom STB SoCs");
+MODULE_LICENSE("GPL");
-- 
2.7.4

[PATCH v4 2/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Markus Mayer]

From: Markus Mayer <mmayer@broadcom.com>

This CPUfreq driver provides basic frequency scaling for older Broadcom
STB SoCs that do not use AVS firmware with DVFS support. There is no
support for voltage scaling.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
---
 drivers/cpufreq/Kconfig.arm       |  12 ++
 drivers/cpufreq/Makefile          |   1 +
 drivers/cpufreq/brcmstb-cpufreq.c | 377 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 390 insertions(+)
 create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 920c469..36422af 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -33,6 +33,18 @@ config ARM_BRCMSTB_AVS_CPUFREQ_DEBUG
 
 	  If in doubt, say N.
 
+config ARM_BRCMSTB_CPUFREQ
+	tristate "Broadcom STB CPUfreq driver"
+	depends on ARCH_BRCMSTB || COMPILE_TEST
+	default y
+	help
+	  Some Broadcom SoCs offer multiple operating frequencies that CPUfreq
+	  can take advantage of to improve energy efficiency.
+
+	  Say Y, if you have a supported Broadcom SoC. If your Broadcom SoC
+	  has AVS firmware with support for frequency and voltage scaling,
+	  say N here and enable ARM_BRCMSTB_AVS_CPUFREQ instead.
+
 config ARM_DT_BL_CPUFREQ
 	tristate "Generic probing via DT for ARM big LITTLE CPUfreq driver"
 	depends on ARM_BIG_LITTLE_CPUFREQ && OF
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index 1e46c39..23700aa 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_ARM_BIG_LITTLE_CPUFREQ)	+= arm_big_little.o
 obj-$(CONFIG_ARM_DT_BL_CPUFREQ)		+= arm_big_little_dt.o
 
 obj-$(CONFIG_ARM_BRCMSTB_AVS_CPUFREQ)	+= brcmstb-avs-cpufreq.o
+obj-$(CONFIG_ARM_BRCMSTB_CPUFREQ)	+= brcmstb-cpufreq.o
 obj-$(CONFIG_ARCH_DAVINCI)		+= davinci-cpufreq.o
 obj-$(CONFIG_UX500_SOC_DB8500)		+= dbx500-cpufreq.o
 obj-$(CONFIG_ARM_EXYNOS5440_CPUFREQ)	+= exynos5440-cpufreq.o
diff --git a/drivers/cpufreq/brcmstb-cpufreq.c b/drivers/cpufreq/brcmstb-cpufreq.c
new file mode 100644
index 0000000..80ac1ae
--- /dev/null
+++ b/drivers/cpufreq/brcmstb-cpufreq.c
@@ -0,0 +1,377 @@
+/*
+ * CPU frequency scaling for Broadcom set top box SoCs
+ *
+ * Copyright (c) 2016 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/cpufreq.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+#define BRCMSTB_CPUFREQ_PREFIX	"brcmstb"
+#define BRCMSTB_CPUFREQ_NAME	BRCMSTB_CPUFREQ_PREFIX "-cpufreq"
+
+/* We search for these compatible strings. */
+#define BRCMSTB_DT_CPU_CLK_CTRL	"brcm,brcmstb-cpu-clk-div"
+#define BRCMSTB_DT_MEMC_DDR	"brcm,brcmstb-memc-ddr"
+#define BRCM_AVS_CPU_DATA	"brcm,avs-cpu-data-mem"
+
+/*
+ * We also need a few clocks in device tree. They are referenced in the
+ * brcm,brcmstb-cpu-clk-div node in device tree, so we can look them up.
+ */
+#define BRCMSTB_CLK_MDIV_CH0	"cpu_mdiv_ch0"
+#define BRCMSTB_CLK_NDIV_INT	"cpu_ndiv_int"
+#define BRCMSTB_CLK_SW_SCB	"sw_scb"
+
+#define BRCMSTB_TBL_SAFE_MODE	BIT(0)
+#define BRCMSTB_REG_SAFE_MODE	BIT(4)
+
+#define TRANSITION_LATENCY	(25 * 1000)	/* 25 us */
+
+/* This is as low as we'll go in the frequency table. */
+#define MIN_CPU_FREQ		(100 * 1000)	/* in kHz */
+
+struct private_data {
+	void __iomem *cpu_clk_ctrl_reg;
+	struct clk *mdiv_clk;
+	struct clk *ndiv_clk;
+	struct clk *sw_scb_clk;
+	struct device *dev;
+};
+
+/* Count the active memory controllers in the system. */
+static int count_memory_controllers(void)
+{
+	struct device_node *np = NULL;
+	int i = 0;
+
+	do {
+		np = of_find_compatible_node(np, NULL, BRCMSTB_DT_MEMC_DDR);
+		if (of_device_is_available(np))
+			i++;
+		of_node_put(np);
+	} while (np);
+
+	return i;
+}
+
+static void get_frequencies(const struct cpufreq_policy *policy,
+			   unsigned int *vco_freq, unsigned int *cpu_freq,
+			   unsigned int *scb_freq)
+{
+	struct private_data *priv = policy->driver_data;
+
+	/* return frequencies in kHz */
+	*vco_freq = clk_get_rate(priv->ndiv_clk) / 1000;
+	*cpu_freq = clk_get_rate(priv->mdiv_clk) / 1000;
+	*scb_freq = clk_get_rate(priv->sw_scb_clk) / 1000;
+}
+
+/*
+ * Safe mode: When set, the CPU's bus unit is being throttled. This is done to
+ * avoid buffer overflows when the CPU-to-bus-clock ratio is low.
+ *
+ * The formula as to what constitutes a low CPU-to-bus-clock ratio takes into
+ * account the number of memory controllers active in the system and the SCB
+ * frequency. More memory controllers means safe mode is required starting at
+ * higher frequencies.
+ *
+ * For 1 memory controller, cpu_freq/scb_freq must be greater than or equal to
+ * 2 to not require safe mode.
+ *
+ * For 2 or 3 memory controllers, cpu_freq/scb_freq must be greater than or
+ * equal 3 to not require safe mode.
+ */
+
+static int freq_requires_safe_mode(unsigned int cpu_freq, unsigned int scb_freq,
+				   int num_memc)
+{
+	unsigned int safe_ratio;
+
+	switch (num_memc) {
+	case 1:
+		safe_ratio = 2;
+		break;
+	case 2:
+	case 3:
+		safe_ratio = 3;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ((cpu_freq / scb_freq) < safe_ratio);
+}
+
+static struct cpufreq_frequency_table *
+brcmstb_get_freq_table(const struct cpufreq_policy *policy)
+{
+	unsigned int cpu_freq, vco_freq, scb_freq, mdiv, init_mdiv, f;
+	struct cpufreq_frequency_table *table;
+	struct private_data *priv;
+	int num_memc, ret;
+	unsigned int i = 0;
+
+	priv = policy->driver_data;
+	num_memc = count_memory_controllers();
+	get_frequencies(policy, &vco_freq, &cpu_freq, &scb_freq);
+
+	/* Calculate the initial mdiv value. We'll increment mdiv from here. */
+	init_mdiv = vco_freq / cpu_freq;
+
+	/* Count how many frequencies we'll offer. */
+	f = cpu_freq;
+	for (mdiv = init_mdiv; f >= MIN_CPU_FREQ; mdiv++, f = vco_freq / mdiv) {
+		/* We only want to use "whole" MHz. */
+		if ((f % 1000) == 0)
+			i++;
+	}
+
+	table = devm_kzalloc(priv->dev, (i + 1) * sizeof(*table), GFP_KERNEL);
+	if (!table)
+		return ERR_PTR(-ENOMEM);
+
+	/* Now, fill the table. */
+	f = cpu_freq;
+	i = 0;
+	for (mdiv = init_mdiv; f >= MIN_CPU_FREQ; mdiv++, f = vco_freq / mdiv) {
+		if ((f % 1000) == 0) {
+			table[i].frequency = f;
+			ret = freq_requires_safe_mode(f, scb_freq, num_memc);
+			if (ret < 0)
+				return ERR_PTR(ret);
+			if (ret > 0)
+				table[i].driver_data |= BRCMSTB_TBL_SAFE_MODE;
+			i++;
+		}
+	}
+	table[i].frequency = CPUFREQ_TABLE_END;
+
+	return table;
+}
+
+static int brcmstb_target_index(struct cpufreq_policy *policy,
+				unsigned int index)
+{
+	struct cpufreq_frequency_table *entry;
+	struct private_data *priv;
+	int ret, safe_mode_needed;
+	u32 reg;
+
+	priv = policy->driver_data;
+	entry = &policy->freq_table[index];
+	safe_mode_needed = entry->driver_data & BRCMSTB_TBL_SAFE_MODE;
+
+	reg = readl(priv->cpu_clk_ctrl_reg);
+	if (safe_mode_needed && !(reg & BRCMSTB_REG_SAFE_MODE)) {
+		reg |= BRCMSTB_REG_SAFE_MODE;
+		writel(reg, priv->cpu_clk_ctrl_reg);
+	}
+	ret = clk_set_rate(policy->clk, entry->frequency * 1000);
+	if (!ret && !safe_mode_needed && (reg & BRCMSTB_REG_SAFE_MODE)) {
+		reg &= ~BRCMSTB_REG_SAFE_MODE;
+		writel(reg, priv->cpu_clk_ctrl_reg);
+	}
+
+	return ret;
+}
+
+/*
+ * All initialization code that we only want to execute once goes here. Setup
+ * code that can be re-tried on every core (if it failed before) can go into
+ * brcmstb_cpufreq_init().
+ */
+static int brcmstb_prepare_init(struct platform_device *pdev)
+{
+	struct private_data *priv;
+	struct resource *res;
+	struct device *dev;
+
+	/*
+	 * If the BRCM STB AVS CPUfreq driver is supported, we bail, so that
+	 * the more modern approach implementing DVFS in firmware can be used.
+	 */
+	if (IS_ENABLED(CONFIG_ARM_BRCMSTB_AVS_CPUFREQ)) {
+		struct device_node *np;
+
+		np = of_find_compatible_node(NULL, NULL, BRCM_AVS_CPU_DATA);
+		if (np) {
+			of_node_put(np);
+			return -ENXIO;
+		}
+	}
+
+	dev = &pdev->dev;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->cpu_clk_ctrl_reg = devm_ioremap_resource(dev, res);
+	if (IS_ERR(priv->cpu_clk_ctrl_reg)) {
+		dev_err(dev, "couldn't map DT entry %s\n",
+			BRCMSTB_DT_CPU_CLK_CTRL);
+		return -ENODEV;
+	}
+
+	priv->mdiv_clk = devm_clk_get(dev, BRCMSTB_CLK_MDIV_CH0);
+	priv->ndiv_clk = devm_clk_get(dev, BRCMSTB_CLK_NDIV_INT);
+	priv->sw_scb_clk = devm_clk_get(dev, BRCMSTB_CLK_SW_SCB);
+
+	if (IS_ERR(priv->mdiv_clk))
+		return PTR_ERR(priv->mdiv_clk);
+	if (IS_ERR(priv->ndiv_clk))
+		return PTR_ERR(priv->ndiv_clk);
+	if (IS_ERR(priv->sw_scb_clk))
+		return PTR_ERR(priv->sw_scb_clk);
+
+	priv->dev = dev;
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static int brcmstb_cpufreq_init(struct cpufreq_policy *policy)
+{
+	struct cpufreq_frequency_table *freq_table;
+	struct platform_device *pdev;
+	struct private_data *priv;
+	struct device *dev;
+	int ret;
+
+	pdev = cpufreq_get_driver_data();
+	priv = platform_get_drvdata(pdev);
+	dev = &pdev->dev;
+
+	policy->clk = priv->mdiv_clk;
+	policy->driver_data = priv;
+
+	freq_table = brcmstb_get_freq_table(policy);
+	if (IS_ERR(freq_table)) {
+		ret = PTR_ERR(freq_table);
+		dev_err(dev, "Couldn't determine frequency table (%d).\n", ret);
+		if (ret == -EINVAL)
+			dev_emerg(dev,
+				"Invalid number of memory controllers -- %d!\n",
+				count_memory_controllers());
+		return ret;
+	}
+
+	ret = cpufreq_generic_init(policy, freq_table, TRANSITION_LATENCY);
+	if (!ret)
+		dev_info(dev, "registered\n");
+
+	return ret;
+}
+
+/* Shows the number of memory controllers. */
+static ssize_t show_brcmstb_num_memc(struct cpufreq_policy *policy, char *buf)
+{
+	return sprintf(buf, "%u\n", count_memory_controllers());
+}
+
+/* Shows vco_freq, cpu_freq, and scb_freq in kHz. */
+static ssize_t show_brcmstb_freqs(struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int vco_freq, cpu_freq, scb_freq;
+
+	get_frequencies(policy, &vco_freq, &cpu_freq, &scb_freq);
+
+	return sprintf(buf, "%u %u %u\n", vco_freq, cpu_freq, scb_freq);
+}
+
+/* Shows the lowest frequency (in kHz) that can be used without "safe mode". */
+static ssize_t show_brcmstb_safe_freq(struct cpufreq_policy *policy, char *buf)
+{
+	struct cpufreq_frequency_table *entry;
+	unsigned int safe_freq = 0;
+
+	cpufreq_for_each_valid_entry(entry, policy->freq_table) {
+		if (!(entry->driver_data & BRCMSTB_TBL_SAFE_MODE))
+			safe_freq = entry->frequency;
+	}
+
+	return sprintf(buf, "%u\n", safe_freq);
+}
+
+cpufreq_freq_attr_ro(brcmstb_num_memc);
+cpufreq_freq_attr_ro(brcmstb_freqs);
+cpufreq_freq_attr_ro(brcmstb_safe_freq);
+
+static struct freq_attr *brcmstb_cpufreq_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	&brcmstb_num_memc,
+	&brcmstb_freqs,
+	&brcmstb_safe_freq,
+	NULL
+};
+
+static struct cpufreq_driver brcmstb_driver = {
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.verify		= cpufreq_generic_frequency_table_verify,
+	.target_index	= brcmstb_target_index,
+	.get		= cpufreq_generic_get,
+	.init		= brcmstb_cpufreq_init,
+	.attr		= brcmstb_cpufreq_attr,
+	.name		= BRCMSTB_CPUFREQ_PREFIX,
+};
+
+static int brcmstb_cpufreq_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = brcmstb_prepare_init(pdev);
+	if (ret)
+		return ret;
+
+	brcmstb_driver.driver_data = pdev;
+
+	return cpufreq_register_driver(&brcmstb_driver);
+}
+
+static int brcmstb_cpufreq_remove(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = cpufreq_unregister_driver(&brcmstb_driver);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static const struct of_device_id brcmstb_cpufreq_match[] = {
+	{ .compatible = BRCMSTB_DT_CPU_CLK_CTRL },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, brcmstb_cpufreq_match);
+
+static struct platform_driver brcmstb_cpufreq_platdrv = {
+	.driver = {
+		.name	= BRCMSTB_CPUFREQ_NAME,
+		.of_match_table = brcmstb_cpufreq_match,
+	},
+	.probe		= brcmstb_cpufreq_probe,
+	.remove		= brcmstb_cpufreq_remove,
+};
+module_platform_driver(brcmstb_cpufreq_platdrv);
+
+MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
+MODULE_DESCRIPTION("CPUfreq driver for Broadcom STB SoCs");
+MODULE_LICENSE("GPL");
-- 
2.7.4

Re: [PATCH v4 1/2] dt-bindings: brcm: clocks: add binding for brcmstb-cpu-clk-div

[Stephen Boyd]

On 12/20, Markus Mayer wrote:
> From: Markus Mayer <mmayer@broadcom.com>
> 
> Add binding document for brcm,brcmstb-cpu-clk-div.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>  .../bindings/clock/brcm,brcmstb-cpu-clk-div.txt    | 83 ++++++++++++++++++++++
>  MAINTAINERS                                        |  1 +
>  2 files changed, 84 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
> new file mode 100644
> index 0000000..3bc99c5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
> @@ -0,0 +1,83 @@
> +The CPU divider node serves as the sole clock for the CPU complex. It supports
> +power-of-2 clock division, with a divider of "1" as the default highest-speed
> +setting.
> +
> +Required properties:
> +- compatible: shall be "brcm,brcmstb-cpu-clk-div"
> +- reg: address and width of the divider configuration register
> +- #clock-cells: shall be set to 0
> +- clocks: phandle of clock provider which provides the source clock
> +          (this would typically be a "fixed-clock" type PLL)
> +- div-table: list of (raw_value,divider) ordered pairs that correspond to the
> +             allowed clock divider settings
> +- div-shift-width: least-significant bit position and width of divider value
> +
> +Optional properties:
> +- clocks: additional clocks can be specified if needed
> +- clock-names: clocks can be named, so they can be looked up
> +
> +Example:
> +	sw_scb: sw_scb {
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +		clock-frequency = <432000000>;
> +	};
> +

Is this a PLL?

> +	fixed0: fixed0 {
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +		clock-frequency = <54000000>;
> +	};

And perhaps some sort of oscillator?

> +
> +	cpu_pdiv: cpu_pdiv@f04e0008 {
> +		compatible = "divider-clock";
> +		#clock-cells = <0>;
> +		reg = <0xf04e0008 0x4>;
> +		bit-shift = <10>;
> +		bit-mask = <0xf>;
> +		index-starts-at-one;
> +		clocks = <&fixed0>;
> +		clock-names = "fixed0";
> +	};
> +
> +	cpu_ndiv_int: cpu_ndiv_int {
> +		compatible = "fixed-factor-clock";

Ok..

> +		#clock-cells = <0>;
> +		clock-div = <1>;
> +		clock-mult = <167>;
> +		clocks = <&cpu_pdiv>;
> +		clock-names = "cpu_pdiv";
> +	};
> +
> +	cpu_mdiv_ch0: cpu_mdiv_ch0@f04e0000 {
> +		compatible = "divider-clock";

Is there a binding for this?

> +		#clock-cells = <0>;
> +		reg = <0xf04e0000 0x4>;
> +		bit-shift = <1>;
> +		bit-mask = <0xff>;
> +		index-starts-at-one;
> +		clocks = <&cpu_ndiv_int>;
> +		clock-names = "cpu_ndiv_int";
> +	};
> +
> +	cpupll: cpupll@0 {
> +		#clock-cells = <0>;
> +		clock-frequency = <1503000000>;
> +		compatible = "fixed-clock";
> +	};
> +
> +	cpuclkdiv: cpu-clk-div@0 {

Wrong unit address. Should be f03e257c?

> +		#clock-cells = <0>;
> +		clock-names = "cpupll",
> +			"cpu_mdiv_ch0",
> +			"cpu_ndiv_int",
> +			"sw_scb";
> +		clocks = <&cpupll,
> +			&cpu_mdiv_ch0,
> +			&cpu_ndiv_int,
> +			&sw_scb>;
> +		compatible = "brcm,brcmstb-cpu-clk-div";
> +		reg = <0xf03e257c 0x4>;
> +		div-table = <0x00 1>;
> +		div-shift-width = <0 5>;

This entire DT design seems wrong. We don't put these sorts of
register level details into DT. There should be a driver that
knows the type of device that is present and how to drive that
hardware.

>From what I can tell there's something like a mux controller at
0xf04e0000 and then there's some sort of divider controller at
0xf03e0000. Perhaps those are two different devices that need
independent drivers? My wild guess is the PLL control is in those
register regions too, but we're not exposing control of them.
That's ok, but don't put the PLL into the DT as a fixed clock.
Just register it from the driver.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

[PATCH v4 1/2] dt-bindings: brcm: clocks: add binding for brcmstb-cpu-clk-div

[Stephen Boyd]

On 12/20, Markus Mayer wrote:
> From: Markus Mayer <mmayer@broadcom.com>
> 
> Add binding document for brcm,brcmstb-cpu-clk-div.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>  .../bindings/clock/brcm,brcmstb-cpu-clk-div.txt    | 83 ++++++++++++++++++++++
>  MAINTAINERS                                        |  1 +
>  2 files changed, 84 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
> new file mode 100644
> index 0000000..3bc99c5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/brcm,brcmstb-cpu-clk-div.txt
> @@ -0,0 +1,83 @@
> +The CPU divider node serves as the sole clock for the CPU complex. It supports
> +power-of-2 clock division, with a divider of "1" as the default highest-speed
> +setting.
> +
> +Required properties:
> +- compatible: shall be "brcm,brcmstb-cpu-clk-div"
> +- reg: address and width of the divider configuration register
> +- #clock-cells: shall be set to 0
> +- clocks: phandle of clock provider which provides the source clock
> +          (this would typically be a "fixed-clock" type PLL)
> +- div-table: list of (raw_value,divider) ordered pairs that correspond to the
> +             allowed clock divider settings
> +- div-shift-width: least-significant bit position and width of divider value
> +
> +Optional properties:
> +- clocks: additional clocks can be specified if needed
> +- clock-names: clocks can be named, so they can be looked up
> +
> +Example:
> +	sw_scb: sw_scb {
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +		clock-frequency = <432000000>;
> +	};
> +

Is this a PLL?

> +	fixed0: fixed0 {
> +		compatible = "fixed-clock";
> +		#clock-cells = <0>;
> +		clock-frequency = <54000000>;
> +	};

And perhaps some sort of oscillator?

> +
> +	cpu_pdiv: cpu_pdiv at f04e0008 {
> +		compatible = "divider-clock";
> +		#clock-cells = <0>;
> +		reg = <0xf04e0008 0x4>;
> +		bit-shift = <10>;
> +		bit-mask = <0xf>;
> +		index-starts-at-one;
> +		clocks = <&fixed0>;
> +		clock-names = "fixed0";
> +	};
> +
> +	cpu_ndiv_int: cpu_ndiv_int {
> +		compatible = "fixed-factor-clock";

Ok..

> +		#clock-cells = <0>;
> +		clock-div = <1>;
> +		clock-mult = <167>;
> +		clocks = <&cpu_pdiv>;
> +		clock-names = "cpu_pdiv";
> +	};
> +
> +	cpu_mdiv_ch0: cpu_mdiv_ch0 at f04e0000 {
> +		compatible = "divider-clock";

Is there a binding for this?

> +		#clock-cells = <0>;
> +		reg = <0xf04e0000 0x4>;
> +		bit-shift = <1>;
> +		bit-mask = <0xff>;
> +		index-starts-at-one;
> +		clocks = <&cpu_ndiv_int>;
> +		clock-names = "cpu_ndiv_int";
> +	};
> +
> +	cpupll: cpupll at 0 {
> +		#clock-cells = <0>;
> +		clock-frequency = <1503000000>;
> +		compatible = "fixed-clock";
> +	};
> +
> +	cpuclkdiv: cpu-clk-div at 0 {

Wrong unit address. Should be f03e257c?

> +		#clock-cells = <0>;
> +		clock-names = "cpupll",
> +			"cpu_mdiv_ch0",
> +			"cpu_ndiv_int",
> +			"sw_scb";
> +		clocks = <&cpupll,
> +			&cpu_mdiv_ch0,
> +			&cpu_ndiv_int,
> +			&sw_scb>;
> +		compatible = "brcm,brcmstb-cpu-clk-div";
> +		reg = <0xf03e257c 0x4>;
> +		div-table = <0x00 1>;
> +		div-shift-width = <0 5>;

This entire DT design seems wrong. We don't put these sorts of
register level details into DT. There should be a driver that
knows the type of device that is present and how to drive that
hardware.

>From what I can tell there's something like a mux controller at
0xf04e0000 and then there's some sort of divider controller at
0xf03e0000. Perhaps those are two different devices that need
independent drivers? My wild guess is the PLL control is in those
register regions too, but we're not exposing control of them.
That's ok, but don't put the PLL into the DT as a fixed clock.
Just register it from the driver.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v4 2/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Viresh Kumar]

On 20-12-16, 14:55, Markus Mayer wrote:
> From: Markus Mayer <mmayer@broadcom.com>
> 
> This CPUfreq driver provides basic frequency scaling for older Broadcom
> STB SoCs that do not use AVS firmware with DVFS support. There is no
> support for voltage scaling.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>  drivers/cpufreq/Kconfig.arm       |  12 ++
>  drivers/cpufreq/Makefile          |   1 +
>  drivers/cpufreq/brcmstb-cpufreq.c | 377 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 390 insertions(+)
>  create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c

I am fine with this patch as I have already Acked V3 of it. But please fix the
bindings improvement suggested by Stephen first.

-- 
viresh

[PATCH v4 2/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Viresh Kumar]

On 20-12-16, 14:55, Markus Mayer wrote:
> From: Markus Mayer <mmayer@broadcom.com>
> 
> This CPUfreq driver provides basic frequency scaling for older Broadcom
> STB SoCs that do not use AVS firmware with DVFS support. There is no
> support for voltage scaling.
> 
> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
> ---
>  drivers/cpufreq/Kconfig.arm       |  12 ++
>  drivers/cpufreq/Makefile          |   1 +
>  drivers/cpufreq/brcmstb-cpufreq.c | 377 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 390 insertions(+)
>  create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c

I am fine with this patch as I have already Acked V3 of it. But please fix the
bindings improvement suggested by Stephen first.

-- 
viresh

Re: [PATCH v4 2/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Markus Mayer]

On 5 January 2017 at 20:14, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 20-12-16, 14:55, Markus Mayer wrote:
>> From: Markus Mayer <mmayer@broadcom.com>
>>
>> This CPUfreq driver provides basic frequency scaling for older Broadcom
>> STB SoCs that do not use AVS firmware with DVFS support. There is no
>> support for voltage scaling.
>>
>> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
>> ---
>>  drivers/cpufreq/Kconfig.arm       |  12 ++
>>  drivers/cpufreq/Makefile          |   1 +
>>  drivers/cpufreq/brcmstb-cpufreq.c | 377 ++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 390 insertions(+)
>>  create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c
>
> I am fine with this patch as I have already Acked V3 of it. But please fix the
> bindings improvement suggested by Stephen first.

Yes, that is on my list of things to do. I will send an update
hopefully next week.

Thanks,
-Markus

[PATCH v4 2/2] cpufreq: brcmstb-cpufreq: CPUfreq driver for older Broadcom STB SoCs

[Markus Mayer]

On 5 January 2017 at 20:14, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 20-12-16, 14:55, Markus Mayer wrote:
>> From: Markus Mayer <mmayer@broadcom.com>
>>
>> This CPUfreq driver provides basic frequency scaling for older Broadcom
>> STB SoCs that do not use AVS firmware with DVFS support. There is no
>> support for voltage scaling.
>>
>> Signed-off-by: Markus Mayer <mmayer@broadcom.com>
>> ---
>>  drivers/cpufreq/Kconfig.arm       |  12 ++
>>  drivers/cpufreq/Makefile          |   1 +
>>  drivers/cpufreq/brcmstb-cpufreq.c | 377 ++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 390 insertions(+)
>>  create mode 100644 drivers/cpufreq/brcmstb-cpufreq.c
>
> I am fine with this patch as I have already Acked V3 of it. But please fix the
> bindings improvement suggested by Stephen first.

Yes, that is on my list of things to do. I will send an update
hopefully next week.

Thanks,
-Markus