[PATCH 0/3] Hi3660 stubclock drivers

[PATCH 0/3] Hi3660 stubclock drivers

[Kaihua Zhong]

This patchset relies on Hi3660 mailbox drivers.

Kaihua Zhong (2):
  clk: hisilicon: Add support for Hi3660 stub clocks
  arm64: dts: Hi3660: Add binding for stub clock

Leo Yan (1):
  dt-bindings: clk: Hi3660: Document stub clock

 .../devicetree/bindings/clock/hi3660-clock.txt     |   6 +
 arch/arm64/boot/dts/hisilicon/hi3660.dtsi          |   8 +
 drivers/clk/hisilicon/Kconfig                      |   6 +
 drivers/clk/hisilicon/Makefile                     |   1 +
 drivers/clk/hisilicon/clk-hi3660-stub.c            | 195 +++++++++++++++++++++
 include/dt-bindings/clock/hi3660-clock.h           |   7 +
 6 files changed, 223 insertions(+)
 create mode 100644 drivers/clk/hisilicon/clk-hi3660-stub.c

-- 
1.9.1

[PATCH 1/3] dt-bindings: clk: Hi3660: Document stub clock

[Kaihua Zhong]

From: Leo Yan <leo.yan@linaro.org>

Document the DT binding for stub clock which is used for CPU,
GPU and DDR frequency scaling.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 Documentation/devicetree/bindings/clock/hi3660-clock.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/hi3660-clock.txt b/Documentation/devicetree/bindings/clock/hi3660-clock.txt
index 0035a7e..946da7c 100644
--- a/Documentation/devicetree/bindings/clock/hi3660-clock.txt
+++ b/Documentation/devicetree/bindings/clock/hi3660-clock.txt
@@ -13,12 +13,18 @@ Required Properties:
 	- "hisilicon,hi3660-pmuctrl"
 	- "hisilicon,hi3660-sctrl"
 	- "hisilicon,hi3660-iomcu"
+	- "hisilicon,hi3660-stub-clk"
 
 - reg: physical base address of the controller and length of memory mapped
   region.
 
 - #clock-cells: should be 1.
 
+Optional Properties:
+
+- mboxes: Phandle to the mailbox for sending message to MCU.
+            (See: ../mailbox/hisilicon,hi3660-mailbox.txt for more info)
+
 Each clock is assigned an identifier and client nodes use this identifier
 to specify the clock which they consume.
 
-- 
1.9.1

[PATCH 2/3] clk: hisilicon: Add support for Hi3660 stub clocks

[Kaihua Zhong]

Hi3660 has four stub clocks, which are big and LITTLE cluster clocks,
GPU clock and DDR clock.  These clocks ask MCU for frequency scaling
by sending message through mailbox.

This commit adds support for stub clocks, it requests the dedicated
mailbox channel at initialization; then later uses this channel to send
message to MCU to execute frequency scaling. The four stub clocks share
the same mailbox channel, but every stub clock has its own command id so
MCU can distinguish the requirement coming for which clock.

A shared memory is used to present effective frequency value, so the
clock driver uses I/O mapping for the memory and reads back rate value.

Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Kai Zhao <zhaokai1@hisilicon.com>
Signed-off-by: Kevin Wang <kevin.wangtao@hisilicon.com>
Signed-off-by: Ruyi Wang <wangruyi@huawei.com>
Signed-off-by: Kaihua Zhong <zhongkaihua@huawei.com>
---
 drivers/clk/hisilicon/Kconfig            |   6 +
 drivers/clk/hisilicon/Makefile           |   1 +
 drivers/clk/hisilicon/clk-hi3660-stub.c  | 195 +++++++++++++++++++++++++++++++
 include/dt-bindings/clock/hi3660-clock.h |   7 ++
 4 files changed, 209 insertions(+)
 create mode 100644 drivers/clk/hisilicon/clk-hi3660-stub.c

diff --git a/drivers/clk/hisilicon/Kconfig b/drivers/clk/hisilicon/Kconfig
index 7098bfd..1bd4355 100644
--- a/drivers/clk/hisilicon/Kconfig
+++ b/drivers/clk/hisilicon/Kconfig
@@ -49,3 +49,9 @@ config STUB_CLK_HI6220
 	default ARCH_HISI
 	help
 	  Build the Hisilicon Hi6220 stub clock driver.
+
+config STUB_CLK_HI3660
+	bool "Hi3660 Stub Clock Driver"
+	depends on COMMON_CLK_HI3660 && MAILBOX
+	help
+	  Build the Hisilicon Hi3660 stub clock driver.
diff --git a/drivers/clk/hisilicon/Makefile b/drivers/clk/hisilicon/Makefile
index 1e4c3dd..0a5b499 100644
--- a/drivers/clk/hisilicon/Makefile
+++ b/drivers/clk/hisilicon/Makefile
@@ -14,3 +14,4 @@ obj-$(CONFIG_COMMON_CLK_HI3798CV200)	+= crg-hi3798cv200.o
 obj-$(CONFIG_COMMON_CLK_HI6220)	+= clk-hi6220.o
 obj-$(CONFIG_RESET_HISI)	+= reset.o
 obj-$(CONFIG_STUB_CLK_HI6220)	+= clk-hi6220-stub.o
+obj-$(CONFIG_STUB_CLK_HI3660)	+= clk-hi3660-stub.o
diff --git a/drivers/clk/hisilicon/clk-hi3660-stub.c b/drivers/clk/hisilicon/clk-hi3660-stub.c
new file mode 100644
index 0000000..0a21c91
--- /dev/null
+++ b/drivers/clk/hisilicon/clk-hi3660-stub.c
@@ -0,0 +1,195 @@
+/*
+ * Hisilicon clock driver
+ *
+ * Copyright (c) 2013-2017 Hisilicon Limited.
+ * Copyright (c) 2017 Linaro Limited.
+ *
+ * Author: Kai Zhao <zhaokai1@hisilicon.com>
+ * Author: Tao Wang <kevin.wangtao@hisilicon.com>
+ * Author: Leo Yan <leo.yan@linaro.org>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; 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-provider.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <dt-bindings/clock/hi3660-clock.h>
+
+#define HI3660_STUB_CLOCK_DATA		(0x70)
+#define MHZ				(1000 * 1000)
+
+#define DEFINE_CLK_STUB(_id, _cmd, _name)			\
+	{							\
+		.id = (_id),					\
+		.cmd = (_cmd),					\
+		.hw.init = &(struct clk_init_data) {		\
+			.name = #_name,				\
+			.ops = &hi3660_stub_clk_ops,		\
+			.num_parents = 0,			\
+			.flags = CLK_GET_RATE_NOCACHE,		\
+		},						\
+	},
+
+#define to_stub_clk(_hw) container_of(_hw, struct hi3660_stub_clk, hw)
+
+struct hi3660_stub_clk_chan {
+	struct mbox_client cl;
+	struct mbox_chan *mbox;
+};
+
+struct hi3660_stub_clk {
+	unsigned int id;
+	struct device *dev;
+	struct clk_hw hw;
+	unsigned int cmd;
+	unsigned int msg[8];
+	unsigned int rate;
+};
+
+static void __iomem *freq_reg;
+static struct hi3660_stub_clk_chan *chan;
+
+static unsigned long hi3660_stub_clk_recalc_rate(struct clk_hw *hw,
+						 unsigned long parent_rate)
+{
+	struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
+
+	/*
+	 * LPM3 writes back the CPU frequency in shared SRAM so read
+	 * back the frequency.
+	 */
+	stub_clk->rate = readl(freq_reg + (stub_clk->id << 2)) * MHZ;
+	return stub_clk->rate;
+}
+
+static long hi3660_stub_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+				       unsigned long *prate)
+{
+	/*
+	 * LPM3 handles rate rounding so just return whatever
+	 * rate is requested.
+	 */
+	return rate;
+}
+
+static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+				    unsigned long parent_rate)
+{
+	struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
+
+	stub_clk->msg[0] = stub_clk->cmd;
+	stub_clk->msg[1] = rate / MHZ;
+
+	dev_dbg(stub_clk->dev, "set rate msg[0]=0x%x msg[1]=0x%x\n",
+		stub_clk->msg[0], stub_clk->msg[1]);
+
+	mbox_send_message(chan->mbox, stub_clk->msg);
+	mbox_client_txdone(chan->mbox, 0);
+
+	stub_clk->rate = rate;
+	return 0;
+}
+
+static const struct clk_ops hi3660_stub_clk_ops = {
+	.recalc_rate    = hi3660_stub_clk_recalc_rate,
+	.round_rate     = hi3660_stub_clk_round_rate,
+	.set_rate       = hi3660_stub_clk_set_rate,
+};
+
+static struct hi3660_stub_clk hi3660_stub_clks[HI3660_CLK_STUB_NUM] = {
+	DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER0, 0x0001030A, "cpu-cluster.0")
+	DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER1, 0x0002030A, "cpu-cluster.1")
+	DEFINE_CLK_STUB(HI3660_CLK_STUB_GPU, 0x0003030A, "clk-g3d")
+	DEFINE_CLK_STUB(HI3660_CLK_STUB_DDR, 0x00040309, "clk-ddrc")
+};
+
+static struct clk_hw *hi3660_stub_clk_hw_get(struct of_phandle_args *clkspec,
+					     void *data)
+{
+	unsigned int idx = clkspec->args[0];
+
+	if (idx > HI3660_CLK_STUB_NUM) {
+		pr_err("%s: invalid index %u\n", __func__, idx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return &hi3660_stub_clks[idx].hw;
+}
+
+static int hi3660_stub_clk_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	unsigned int i;
+	int ret;
+
+	chan = devm_kzalloc(dev, sizeof(*chan), GFP_KERNEL);
+	if (!chan)
+		return -ENOMEM;
+
+	/* Use mailbox client without blocking */
+	chan->cl.dev = dev;
+	chan->cl.tx_done = NULL;
+	chan->cl.tx_block = false;
+	chan->cl.knows_txdone = false;
+
+	/* Allocate mailbox channel */
+	chan->mbox = mbox_request_channel(&chan->cl, 0);
+	if (IS_ERR(chan->mbox))
+		return PTR_ERR(chan->mbox);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	freq_reg = devm_ioremap(dev, res->start, resource_size(res));
+	if (IS_ERR(freq_reg))
+		return -ENOMEM;
+
+	freq_reg += HI3660_STUB_CLOCK_DATA;
+
+	for (i = 0; i < HI3660_CLK_STUB_NUM; i++) {
+		hi3660_stub_clks[i].dev = dev;
+		ret = devm_clk_hw_register(&pdev->dev, &hi3660_stub_clks[i].hw);
+		if (ret)
+			return ret;
+	}
+
+	ret = of_clk_add_hw_provider(pdev->dev.of_node, hi3660_stub_clk_hw_get,
+				     hi3660_stub_clks);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct of_device_id hi3660_stub_clk_of_match[] = {
+	{ .compatible = "hisilicon,hi3660-stub-clk", },
+	{}
+};
+
+static struct platform_driver hi3660_stub_clk_driver = {
+	.probe	= hi3660_stub_clk_probe,
+	.driver = {
+		.name = "hi3660-stub-clk",
+		.of_match_table = hi3660_stub_clk_of_match,
+	},
+};
+
+static int __init hi3660_stub_clk_init(void)
+{
+	return platform_driver_register(&hi3660_stub_clk_driver);
+}
+subsys_initcall(hi3660_stub_clk_init);
diff --git a/include/dt-bindings/clock/hi3660-clock.h b/include/dt-bindings/clock/hi3660-clock.h
index adb768d..75d583e 100644
--- a/include/dt-bindings/clock/hi3660-clock.h
+++ b/include/dt-bindings/clock/hi3660-clock.h
@@ -208,4 +208,11 @@
 #define HI3660_CLK_I2C6_IOMCU		3
 #define HI3660_CLK_IOMCU_PERI0		4
 
+/* clk in stub clock */
+#define HI3660_CLK_STUB_CLUSTER0	0
+#define HI3660_CLK_STUB_CLUSTER1	1
+#define HI3660_CLK_STUB_GPU		2
+#define HI3660_CLK_STUB_DDR		3
+#define HI3660_CLK_STUB_NUM		4
+
 #endif	/* __DTS_HI3660_CLOCK_H */
-- 
1.9.1

[PATCH 3/3] arm64: dts: Hi3660: Add binding for stub clock

[Kaihua Zhong]

Add DT binding for Hi3660 stub clock driver.

Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Kai Zhao <zhaokai1@hisilicon.com>
Signed-off-by: Kevin Wang <kevin.wangtao@hisilicon.com>
Signed-off-by: Ruyi Wang <wangruyi@huawei.com>
Signed-off-by: Kaihua Zhong <zhongkaihua@huawei.com>
---
 arch/arm64/boot/dts/hisilicon/hi3660.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
index b7a90d6..89a2a13 100644
--- a/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
+++ b/arch/arm64/boot/dts/hisilicon/hi3660.dtsi
@@ -285,6 +285,14 @@
 			#reset-cells = <2>;
 		};
 
+		stub_clock: stub_clock {
+			compatible = "hisilicon,hi3660-stub-clk";
+			reg = <0x0 0xe896b500 0x0 0x0100>;
+			#clock-cells = <1>;
+			x-names = "mbox-tx";
+			xes = <&mailbox 13 3 0>;
+		};
+
 		dual_timer0: timer@fff14000 {
 			compatible = "arm,sp804", "arm,primecell";
 			reg = <0x0 0xfff14000 0x0 0x1000>;
-- 
1.9.1

Re: [PATCH 2/3] clk: hisilicon: Add support for Hi3660 stub clocks

[Julien Thierry]

Hi Kaihua,

On 03/11/17 07:25, Kaihua Zhong wrote:
> Hi3660 has four stub clocks, which are big and LITTLE cluster clocks,
> GPU clock and DDR clock.  These clocks ask MCU for frequency scaling
> by sending message through mailbox.
> 
> This commit adds support for stub clocks, it requests the dedicated
> mailbox channel at initialization; then later uses this channel to send
> message to MCU to execute frequency scaling. The four stub clocks share
> the same mailbox channel, but every stub clock has its own command id so
> MCU can distinguish the requirement coming for which clock.
> 
> A shared memory is used to present effective frequency value, so the
> clock driver uses I/O mapping for the memory and reads back rate value.
> 
> Reviewed-by: Leo Yan <leo.yan@linaro.org>
> Signed-off-by: Kai Zhao <zhaokai1@hisilicon.com>
> Signed-off-by: Kevin Wang <kevin.wangtao@hisilicon.com>
> Signed-off-by: Ruyi Wang <wangruyi@huawei.com>
> Signed-off-by: Kaihua Zhong <zhongkaihua@huawei.com>
> ---
>   drivers/clk/hisilicon/Kconfig            |   6 +
>   drivers/clk/hisilicon/Makefile           |   1 +
>   drivers/clk/hisilicon/clk-hi3660-stub.c  | 195 +++++++++++++++++++++++++++++++
>   include/dt-bindings/clock/hi3660-clock.h |   7 ++
>   4 files changed, 209 insertions(+)
>   create mode 100644 drivers/clk/hisilicon/clk-hi3660-stub.c
> 
> diff --git a/drivers/clk/hisilicon/Kconfig b/drivers/clk/hisilicon/Kconfig
> index 7098bfd..1bd4355 100644
> --- a/drivers/clk/hisilicon/Kconfig
> +++ b/drivers/clk/hisilicon/Kconfig
> @@ -49,3 +49,9 @@ config STUB_CLK_HI6220
>   	default ARCH_HISI
>   	help
>   	  Build the Hisilicon Hi6220 stub clock driver.
> +
> +config STUB_CLK_HI3660
> +	bool "Hi3660 Stub Clock Driver"
> +	depends on COMMON_CLK_HI3660 && MAILBOX
> +	help
> +	  Build the Hisilicon Hi3660 stub clock driver.
> diff --git a/drivers/clk/hisilicon/Makefile b/drivers/clk/hisilicon/Makefile
> index 1e4c3dd..0a5b499 100644
> --- a/drivers/clk/hisilicon/Makefile
> +++ b/drivers/clk/hisilicon/Makefile
> @@ -14,3 +14,4 @@ obj-$(CONFIG_COMMON_CLK_HI3798CV200)	+= crg-hi3798cv200.o
>   obj-$(CONFIG_COMMON_CLK_HI6220)	+= clk-hi6220.o
>   obj-$(CONFIG_RESET_HISI)	+= reset.o
>   obj-$(CONFIG_STUB_CLK_HI6220)	+= clk-hi6220-stub.o
> +obj-$(CONFIG_STUB_CLK_HI3660)	+= clk-hi3660-stub.o
> diff --git a/drivers/clk/hisilicon/clk-hi3660-stub.c b/drivers/clk/hisilicon/clk-hi3660-stub.c
> new file mode 100644
> index 0000000..0a21c91
> --- /dev/null
> +++ b/drivers/clk/hisilicon/clk-hi3660-stub.c
> @@ -0,0 +1,195 @@
> +/*
> + * Hisilicon clock driver
> + *
> + * Copyright (c) 2013-2017 Hisilicon Limited.
> + * Copyright (c) 2017 Linaro Limited.
> + *
> + * Author: Kai Zhao <zhaokai1@hisilicon.com>
> + * Author: Tao Wang <kevin.wangtao@hisilicon.com>
> + * Author: Leo Yan <leo.yan@linaro.org>
> + *
> + * 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; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; 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-provider.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <dt-bindings/clock/hi3660-clock.h>
> +
> +#define HI3660_STUB_CLOCK_DATA		(0x70)
> +#define MHZ				(1000 * 1000)
> +
> +#define DEFINE_CLK_STUB(_id, _cmd, _name)			\
> +	{							\
> +		.id = (_id),					\
> +		.cmd = (_cmd),					\
> +		.hw.init = &(struct clk_init_data) {		\
> +			.name = #_name,				\
> +			.ops = &hi3660_stub_clk_ops,		\
> +			.num_parents = 0,			\
> +			.flags = CLK_GET_RATE_NOCACHE,		\
> +		},						\
> +	},
> +
> +#define to_stub_clk(_hw) container_of(_hw, struct hi3660_stub_clk, hw)
> +
> +struct hi3660_stub_clk_chan {
> +	struct mbox_client cl;
> +	struct mbox_chan *mbox;
> +};
> +
> +struct hi3660_stub_clk {
> +	unsigned int id;
> +	struct device *dev;

I don't understand why you need to keep this. The only place it is used 
it for the debug message in hi3660_stub_clk_set_rate and you could get 
the device pointer by doing chan->cl.dev since all the stub_clk point to 
the same device.

> +	struct clk_hw hw;
> +	unsigned int cmd;
> +	unsigned int msg[8];
> +	unsigned int rate;
> +};
> +
> +static void __iomem *freq_reg;
> +static struct hi3660_stub_clk_chan *chan;

I would suggest having a slightly longer name than "chan" as this can 
easily get shadowed which is bad for a non-local variable.

Also, maybe you could not declare it as a pointer and avoid the need for 
kzalloc in the probe function.

> +
> +static unsigned long hi3660_stub_clk_recalc_rate(struct clk_hw *hw,
> +						 unsigned long parent_rate)
> +{
> +	struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
> +
> +	/*
> +	 * LPM3 writes back the CPU frequency in shared SRAM so read
> +	 * back the frequency.
> +	 */
> +	stub_clk->rate = readl(freq_reg + (stub_clk->id << 2)) * MHZ;
> +	return stub_clk->rate;
> +}
> +
> +static long hi3660_stub_clk_round_rate(struct clk_hw *hw, unsigned long rate,
> +				       unsigned long *prate)
> +{
> +	/*
> +	 * LPM3 handles rate rounding so just return whatever
> +	 * rate is requested.
> +	 */
> +	return rate;
> +}
> +
> +static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> +				    unsigned long parent_rate)
> +{
> +	struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
> +
> +	stub_clk->msg[0] = stub_clk->cmd;
> +	stub_clk->msg[1] = rate / MHZ;
> +
> +	dev_dbg(stub_clk->dev, "set rate msg[0]=0x%x msg[1]=0x%x\n",
> +		stub_clk->msg[0], stub_clk->msg[1]);
> +
> +	mbox_send_message(chan->mbox, stub_clk->msg);
> +	mbox_client_txdone(chan->mbox, 0);
> +
> +	stub_clk->rate = rate;
> +	return 0;
> +}
> +
> +static const struct clk_ops hi3660_stub_clk_ops = {
> +	.recalc_rate    = hi3660_stub_clk_recalc_rate,
> +	.round_rate     = hi3660_stub_clk_round_rate,
> +	.set_rate       = hi3660_stub_clk_set_rate,
> +};
> +
> +static struct hi3660_stub_clk hi3660_stub_clks[HI3660_CLK_STUB_NUM] = {
> +	DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER0, 0x0001030A, "cpu-cluster.0")
> +	DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER1, 0x0002030A, "cpu-cluster.1")
> +	DEFINE_CLK_STUB(HI3660_CLK_STUB_GPU, 0x0003030A, "clk-g3d")
> +	DEFINE_CLK_STUB(HI3660_CLK_STUB_DDR, 0x00040309, "clk-ddrc")
> +};
> +
> +static struct clk_hw *hi3660_stub_clk_hw_get(struct of_phandle_args *clkspec,
> +					     void *data)
> +{
> +	unsigned int idx = clkspec->args[0];
> +
> +	if (idx > HI3660_CLK_STUB_NUM) {
> +		pr_err("%s: invalid index %u\n", __func__, idx);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	return &hi3660_stub_clks[idx].hw;
> +}
> +
> +static int hi3660_stub_clk_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct resource *res;
> +	unsigned int i;
> +	int ret;
> +
> +	chan = devm_kzalloc(dev, sizeof(*chan), GFP_KERNEL);
> +	if (!chan)
> +		return -ENOMEM;
> +
> +	/* Use mailbox client without blocking */
> +	chan->cl.dev = dev;
> +	chan->cl.tx_done = NULL;
> +	chan->cl.tx_block = false;
> +	chan->cl.knows_txdone = false;
> +
> +	/* Allocate mailbox channel */
> +	chan->mbox = mbox_request_channel(&chan->cl, 0);
> +	if (IS_ERR(chan->mbox))
> +		return PTR_ERR(chan->mbox);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	freq_reg = devm_ioremap(dev, res->start, resource_size(res));
> +	if (IS_ERR(freq_reg))
> +		return -ENOMEM;
> +
> +	freq_reg += HI3660_STUB_CLOCK_DATA;
> +
> +	for (i = 0; i < HI3660_CLK_STUB_NUM; i++) {
> +		hi3660_stub_clks[i].dev = dev;
> +		ret = devm_clk_hw_register(&pdev->dev, &hi3660_stub_clks[i].hw);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	ret = of_clk_add_hw_provider(pdev->dev.of_node, hi3660_stub_clk_hw_get,
> +				     hi3660_stub_clks);
> +	if (ret)
> +		return ret;
> +
> +	return 0;

Hmmm, you could just return ret here without needing the branch.

Cheers,

-- 
Julien Thierry

Re: [PATCH 1/3] dt-bindings: clk: Hi3660: Document stub clock

[Rob Herring]

On Fri, Nov 03, 2017 at 03:25:05PM +0800, Kaihua Zhong wrote:
> From: Leo Yan <leo.yan@linaro.org>
> 
> Document the DT binding for stub clock which is used for CPU,
> GPU and DDR frequency scaling.
> 
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>  Documentation/devicetree/bindings/clock/hi3660-clock.txt | 6 ++++++
>  1 file changed, 6 insertions(+)

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

Re: [PATCH 2/3] clk: hisilicon: Add support for Hi3660 stub clocks

[Rob Herring]

On Fri, Nov 03, 2017 at 03:25:06PM +0800, Kaihua Zhong wrote:
> Hi3660 has four stub clocks, which are big and LITTLE cluster clocks,
> GPU clock and DDR clock.  These clocks ask MCU for frequency scaling
> by sending message through mailbox.
> 
> This commit adds support for stub clocks, it requests the dedicated
> mailbox channel at initialization; then later uses this channel to send
> message to MCU to execute frequency scaling. The four stub clocks share
> the same mailbox channel, but every stub clock has its own command id so
> MCU can distinguish the requirement coming for which clock.
> 
> A shared memory is used to present effective frequency value, so the
> clock driver uses I/O mapping for the memory and reads back rate value.
> 
> Reviewed-by: Leo Yan <leo.yan@linaro.org>
> Signed-off-by: Kai Zhao <zhaokai1@hisilicon.com>
> Signed-off-by: Kevin Wang <kevin.wangtao@hisilicon.com>
> Signed-off-by: Ruyi Wang <wangruyi@huawei.com>
> Signed-off-by: Kaihua Zhong <zhongkaihua@huawei.com>
> ---
>  drivers/clk/hisilicon/Kconfig            |   6 +
>  drivers/clk/hisilicon/Makefile           |   1 +
>  drivers/clk/hisilicon/clk-hi3660-stub.c  | 195 +++++++++++++++++++++++++++++++

>  include/dt-bindings/clock/hi3660-clock.h |   7 ++

This belongs in the binding doc patch. But no need to respin just for 
that. 

>  4 files changed, 209 insertions(+)
>  create mode 100644 drivers/clk/hisilicon/clk-hi3660-stub.c

Re: [PATCH 1/3] dt-bindings: clk: Hi3660: Document stub clock

[Leo Yan]

On Mon, Nov 06, 2017 at 04:13:37PM -0600, Rob Herring wrote:
> On Fri, Nov 03, 2017 at 03:25:05PM +0800, Kaihua Zhong wrote:
> > From: Leo Yan <leo.yan@linaro.org>
> > 
> > Document the DT binding for stub clock which is used for CPU,
> > GPU and DDR frequency scaling.
> > 
> > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > ---
> >  Documentation/devicetree/bindings/clock/hi3660-clock.txt | 6 ++++++
> >  1 file changed, 6 insertions(+)
> 
> Acked-by: Rob Herring <robh@kernel.org>

Thanks, Rob.

And will refactor the dt binding header in next version with other
comments.

Thanks,
Leo Yan

Re: [PATCH 2/3] clk: hisilicon: Add support for Hi3660 stub clocks

[Leo Yan]

Hi Julien,

On Fri, Nov 03, 2017 at 05:37:34PM +0000, Julien Thierry wrote:
> Hi Kaihua,
> 
> On 03/11/17 07:25, Kaihua Zhong wrote:
> >Hi3660 has four stub clocks, which are big and LITTLE cluster clocks,
> >GPU clock and DDR clock.  These clocks ask MCU for frequency scaling
> >by sending message through mailbox.
> >
> >This commit adds support for stub clocks, it requests the dedicated
> >mailbox channel at initialization; then later uses this channel to send
> >message to MCU to execute frequency scaling. The four stub clocks share
> >the same mailbox channel, but every stub clock has its own command id so
> >MCU can distinguish the requirement coming for which clock.
> >
> >A shared memory is used to present effective frequency value, so the
> >clock driver uses I/O mapping for the memory and reads back rate value.
> >
> >Reviewed-by: Leo Yan <leo.yan@linaro.org>
> >Signed-off-by: Kai Zhao <zhaokai1@hisilicon.com>
> >Signed-off-by: Kevin Wang <kevin.wangtao@hisilicon.com>
> >Signed-off-by: Ruyi Wang <wangruyi@huawei.com>
> >Signed-off-by: Kaihua Zhong <zhongkaihua@huawei.com>
> >---
> >  drivers/clk/hisilicon/Kconfig            |   6 +
> >  drivers/clk/hisilicon/Makefile           |   1 +
> >  drivers/clk/hisilicon/clk-hi3660-stub.c  | 195 +++++++++++++++++++++++++++++++
> >  include/dt-bindings/clock/hi3660-clock.h |   7 ++
> >  4 files changed, 209 insertions(+)
> >  create mode 100644 drivers/clk/hisilicon/clk-hi3660-stub.c
> >
> >diff --git a/drivers/clk/hisilicon/Kconfig b/drivers/clk/hisilicon/Kconfig
> >index 7098bfd..1bd4355 100644
> >--- a/drivers/clk/hisilicon/Kconfig
> >+++ b/drivers/clk/hisilicon/Kconfig
> >@@ -49,3 +49,9 @@ config STUB_CLK_HI6220
> >  	default ARCH_HISI
> >  	help
> >  	  Build the Hisilicon Hi6220 stub clock driver.
> >+
> >+config STUB_CLK_HI3660
> >+	bool "Hi3660 Stub Clock Driver"
> >+	depends on COMMON_CLK_HI3660 && MAILBOX
> >+	help
> >+	  Build the Hisilicon Hi3660 stub clock driver.
> >diff --git a/drivers/clk/hisilicon/Makefile b/drivers/clk/hisilicon/Makefile
> >index 1e4c3dd..0a5b499 100644
> >--- a/drivers/clk/hisilicon/Makefile
> >+++ b/drivers/clk/hisilicon/Makefile
> >@@ -14,3 +14,4 @@ obj-$(CONFIG_COMMON_CLK_HI3798CV200)	+= crg-hi3798cv200.o
> >  obj-$(CONFIG_COMMON_CLK_HI6220)	+= clk-hi6220.o
> >  obj-$(CONFIG_RESET_HISI)	+= reset.o
> >  obj-$(CONFIG_STUB_CLK_HI6220)	+= clk-hi6220-stub.o
> >+obj-$(CONFIG_STUB_CLK_HI3660)	+= clk-hi3660-stub.o
> >diff --git a/drivers/clk/hisilicon/clk-hi3660-stub.c b/drivers/clk/hisilicon/clk-hi3660-stub.c
> >new file mode 100644
> >index 0000000..0a21c91
> >--- /dev/null
> >+++ b/drivers/clk/hisilicon/clk-hi3660-stub.c
> >@@ -0,0 +1,195 @@
> >+/*
> >+ * Hisilicon clock driver
> >+ *
> >+ * Copyright (c) 2013-2017 Hisilicon Limited.
> >+ * Copyright (c) 2017 Linaro Limited.
> >+ *
> >+ * Author: Kai Zhao <zhaokai1@hisilicon.com>
> >+ * Author: Tao Wang <kevin.wangtao@hisilicon.com>
> >+ * Author: Leo Yan <leo.yan@linaro.org>
> >+ *
> >+ * 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; either version 2 of the License, or
> >+ * (at your option) any later version.
> >+ *
> >+ * This program is distributed in the hope that it will be useful,
> >+ * but WITHOUT ANY WARRANTY; 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-provider.h>
> >+#include <linux/device.h>
> >+#include <linux/err.h>
> >+#include <linux/init.h>
> >+#include <linux/mailbox_client.h>
> >+#include <linux/module.h>
> >+#include <linux/of.h>
> >+#include <linux/platform_device.h>
> >+#include <dt-bindings/clock/hi3660-clock.h>
> >+
> >+#define HI3660_STUB_CLOCK_DATA		(0x70)
> >+#define MHZ				(1000 * 1000)
> >+
> >+#define DEFINE_CLK_STUB(_id, _cmd, _name)			\
> >+	{							\
> >+		.id = (_id),					\
> >+		.cmd = (_cmd),					\
> >+		.hw.init = &(struct clk_init_data) {		\
> >+			.name = #_name,				\
> >+			.ops = &hi3660_stub_clk_ops,		\
> >+			.num_parents = 0,			\
> >+			.flags = CLK_GET_RATE_NOCACHE,		\
> >+		},						\
> >+	},
> >+
> >+#define to_stub_clk(_hw) container_of(_hw, struct hi3660_stub_clk, hw)
> >+
> >+struct hi3660_stub_clk_chan {
> >+	struct mbox_client cl;
> >+	struct mbox_chan *mbox;
> >+};
> >+
> >+struct hi3660_stub_clk {
> >+	unsigned int id;
> >+	struct device *dev;
> 
> I don't understand why you need to keep this. The only place it is used it
> for the debug message in hi3660_stub_clk_set_rate and you could get the
> device pointer by doing chan->cl.dev since all the stub_clk point to the
> same device.

Kaihua might miss this email, so I checked all your comments; accept
these comments and will spin for next version patch.

Thank you for good suggestions.

Thanks,
Leo Yan

> >+	struct clk_hw hw;
> >+	unsigned int cmd;
> >+	unsigned int msg[8];
> >+	unsigned int rate;
> >+};
> >+
> >+static void __iomem *freq_reg;
> >+static struct hi3660_stub_clk_chan *chan;
> 
> I would suggest having a slightly longer name than "chan" as this can easily
> get shadowed which is bad for a non-local variable.
> 
> Also, maybe you could not declare it as a pointer and avoid the need for
> kzalloc in the probe function.
> 
> >+
> >+static unsigned long hi3660_stub_clk_recalc_rate(struct clk_hw *hw,
> >+						 unsigned long parent_rate)
> >+{
> >+	struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
> >+
> >+	/*
> >+	 * LPM3 writes back the CPU frequency in shared SRAM so read
> >+	 * back the frequency.
> >+	 */
> >+	stub_clk->rate = readl(freq_reg + (stub_clk->id << 2)) * MHZ;
> >+	return stub_clk->rate;
> >+}
> >+
> >+static long hi3660_stub_clk_round_rate(struct clk_hw *hw, unsigned long rate,
> >+				       unsigned long *prate)
> >+{
> >+	/*
> >+	 * LPM3 handles rate rounding so just return whatever
> >+	 * rate is requested.
> >+	 */
> >+	return rate;
> >+}
> >+
> >+static int hi3660_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> >+				    unsigned long parent_rate)
> >+{
> >+	struct hi3660_stub_clk *stub_clk = to_stub_clk(hw);
> >+
> >+	stub_clk->msg[0] = stub_clk->cmd;
> >+	stub_clk->msg[1] = rate / MHZ;
> >+
> >+	dev_dbg(stub_clk->dev, "set rate msg[0]=0x%x msg[1]=0x%x\n",
> >+		stub_clk->msg[0], stub_clk->msg[1]);
> >+
> >+	mbox_send_message(chan->mbox, stub_clk->msg);
> >+	mbox_client_txdone(chan->mbox, 0);
> >+
> >+	stub_clk->rate = rate;
> >+	return 0;
> >+}
> >+
> >+static const struct clk_ops hi3660_stub_clk_ops = {
> >+	.recalc_rate    = hi3660_stub_clk_recalc_rate,
> >+	.round_rate     = hi3660_stub_clk_round_rate,
> >+	.set_rate       = hi3660_stub_clk_set_rate,
> >+};
> >+
> >+static struct hi3660_stub_clk hi3660_stub_clks[HI3660_CLK_STUB_NUM] = {
> >+	DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER0, 0x0001030A, "cpu-cluster.0")
> >+	DEFINE_CLK_STUB(HI3660_CLK_STUB_CLUSTER1, 0x0002030A, "cpu-cluster.1")
> >+	DEFINE_CLK_STUB(HI3660_CLK_STUB_GPU, 0x0003030A, "clk-g3d")
> >+	DEFINE_CLK_STUB(HI3660_CLK_STUB_DDR, 0x00040309, "clk-ddrc")
> >+};
> >+
> >+static struct clk_hw *hi3660_stub_clk_hw_get(struct of_phandle_args *clkspec,
> >+					     void *data)
> >+{
> >+	unsigned int idx = clkspec->args[0];
> >+
> >+	if (idx > HI3660_CLK_STUB_NUM) {
> >+		pr_err("%s: invalid index %u\n", __func__, idx);
> >+		return ERR_PTR(-EINVAL);
> >+	}
> >+
> >+	return &hi3660_stub_clks[idx].hw;
> >+}
> >+
> >+static int hi3660_stub_clk_probe(struct platform_device *pdev)
> >+{
> >+	struct device *dev = &pdev->dev;
> >+	struct resource *res;
> >+	unsigned int i;
> >+	int ret;
> >+
> >+	chan = devm_kzalloc(dev, sizeof(*chan), GFP_KERNEL);
> >+	if (!chan)
> >+		return -ENOMEM;
> >+
> >+	/* Use mailbox client without blocking */
> >+	chan->cl.dev = dev;
> >+	chan->cl.tx_done = NULL;
> >+	chan->cl.tx_block = false;
> >+	chan->cl.knows_txdone = false;
> >+
> >+	/* Allocate mailbox channel */
> >+	chan->mbox = mbox_request_channel(&chan->cl, 0);
> >+	if (IS_ERR(chan->mbox))
> >+		return PTR_ERR(chan->mbox);
> >+
> >+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >+	freq_reg = devm_ioremap(dev, res->start, resource_size(res));
> >+	if (IS_ERR(freq_reg))
> >+		return -ENOMEM;
> >+
> >+	freq_reg += HI3660_STUB_CLOCK_DATA;
> >+
> >+	for (i = 0; i < HI3660_CLK_STUB_NUM; i++) {
> >+		hi3660_stub_clks[i].dev = dev;
> >+		ret = devm_clk_hw_register(&pdev->dev, &hi3660_stub_clks[i].hw);
> >+		if (ret)
> >+			return ret;
> >+	}
> >+
> >+	ret = of_clk_add_hw_provider(pdev->dev.of_node, hi3660_stub_clk_hw_get,
> >+				     hi3660_stub_clks);
> >+	if (ret)
> >+		return ret;
> >+
> >+	return 0;
> 
> Hmmm, you could just return ret here without needing the branch.
> 
> Cheers,
> 
> -- 
> Julien Thierry