Date:	Tue, 5 Jan 2016 20:15:31 +0800
From:	xuejiancheng <xuejiancheng@...wei.com>
To:	Philipp Zabel <p.zabel@...gutronix.de>
CC:	<mturquette@...libre.com>, <sboyd@...eaurora.org>,
	<robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
	<linux@....linux.org.uk>, <khilman@...aro.org>, <arnd@...db.de>,
	<olof@...om.net>, <xuwei5@...ilicon.com>,
	<haojian.zhuang@...aro.org>, <zhangfei.gao@...aro.org>,
	<bintian.wang@...wei.com>, <suwenping@...ilicon.com>,
	<devicetree@...r.kernel.org>, <yanhaifeng@...ilicon.com>,
	<linux-kernel@...r.kernel.org>, <gaofei@...ilicon.com>,
	<ml.yang@...ilicon.com>, <yanghongwei@...ilicon.com>,
	<zhangzhenxing@...ilicon.com>, <linux-clk@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v4 1/6] clk: hisilicon: add CRG driver for hi3519 soc

Hi Philipp,
   Thank you very much for your quick reply.

On 2016/1/5 18:12, Philipp Zabel wrote:
> H Jiancheng,
> 
> Am Mittwoch, den 30.12.2015, 09:43 +0800 schrieb Jiancheng Xue:
>> The CRG(Clock and Reset Generator) block provides clock
>> and reset signals for other modules in hi3519 soc.
>>
>> Signed-off-by: Jiancheng Xue <xuejiancheng@...wei.com>
>> ---
>>  .../devicetree/bindings/clock/hi3519-crg.txt       |  46 +++++++
>>  drivers/clk/hisilicon/Kconfig                      |   7 +
>>  drivers/clk/hisilicon/Makefile                     |   2 +
>>  drivers/clk/hisilicon/clk-hi3519.c                 | 103 ++++++++++++++
>>  drivers/clk/hisilicon/reset.c                      | 149 +++++++++++++++++++++
>>  drivers/clk/hisilicon/reset.h                      |  32 +++++
>>  include/dt-bindings/clock/hi3519-clock.h           |  43 ++++++
>>  7 files changed, 382 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/clock/hi3519-crg.txt
>>  create mode 100644 drivers/clk/hisilicon/clk-hi3519.c
>>  create mode 100644 drivers/clk/hisilicon/reset.c
>>  create mode 100644 drivers/clk/hisilicon/reset.h
>>  create mode 100644 include/dt-bindings/clock/hi3519-clock.h
>>
>> diff --git a/Documentation/devicetree/bindings/clock/hi3519-crg.txt b/Documentation/devicetree/bindings/clock/hi3519-crg.txt
>> new file mode 100644
>> index 0000000..2d23950
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/hi3519-crg.txt
>> @@ -0,0 +1,46 @@
>> +* Hisilicon Hi3519 Clock and Reset Generator(CRG)
>> +
>> +The Hi3519 CRG module provides clock and reset signals to various
>> +controllers within the SoC.
>> +
>> +This binding uses the following bindings:
>> +    Documentation/devicetree/bindings/clock/clock-bindings.txt
>> +    Documentation/devicetree/bindings/reset/reset.txt
>> +
>> +Required Properties:
>> +
>> +- compatible: should be one of the following.
>> +  - "hisilicon,hi3519-crg" - controller compatible with Hi3519 SoC.
>> +
>> +- reg: physical base address of the controller and length of memory mapped
>> +  region.
>> +
>> +- #clock-cells: should be 1.
>> +
>> +Each clock is assigned an identifier and client nodes use this identifier
>> +to specify the clock which they consume.
>> +
>> +All these identifier could be found in <dt-bindings/clock/hi3519-clock.h>.
>> +
>> +- #reset-cells: should be 2.
>> +
>> +A reset signal can be controlled by writing a bit register in the CRG module.
>> +The reset specifier consists of two cells. The first cell represents the
>> +register offset relative to the base address. The second cell represents the
>> +bit index in the register.
> 
> Are the resets controlled by single bits spread around the register
> space? If so, I'm fine with this binding.
> 

Yes, you are right.

>> +Example: CRG nodes
>> +CRG: clock-reset-controller@...10000 {
>> +	compatible = "hisilicon,hi3519-crg";
>> +        reg = <0x12010000 0x10000>;
>> +        #clock-cells = <1>;
>> +        #reset-cells = <2>;
>> +};
>> +
>> +Example: consumer nodes
>> +i2c0: i2c@...10000 {
>> +	compatible = "hisilicon,hi3519-i2c";
>> +        reg = <0x12110000 0x1000>;
>> +        clocks = <&CRG HI3519_I2C0_RST>;*/
>> +        resets = <&CRG 0xe4 0>;
>> +};
>> diff --git a/drivers/clk/hisilicon/Kconfig b/drivers/clk/hisilicon/Kconfig
>> index e434854..b6baebf 100644
>> --- a/drivers/clk/hisilicon/Kconfig
>> +++ b/drivers/clk/hisilicon/Kconfig
>> @@ -1,3 +1,10 @@
>> +config COMMON_CLK_HI3519
>> +	tristate "Clock Driver for Hi3519"
>> +	depends on ARCH_HISI
>> +	default y
>> +	help
>> +	  Build the clock driver for hi3519.
>> +
>>  config COMMON_CLK_HI6220
>>  	bool "Hi6220 Clock Driver"
>>  	depends on ARCH_HISI || COMPILE_TEST
>> diff --git a/drivers/clk/hisilicon/Makefile b/drivers/clk/hisilicon/Makefile
>> index 74dba31..3f57b09 100644
>> --- a/drivers/clk/hisilicon/Makefile
>> +++ b/drivers/clk/hisilicon/Makefile
>> @@ -4,8 +4,10 @@
>>  
>>  obj-y	+= clk.o clkgate-separated.o clkdivider-hi6220.o
>>  
>> +obj-$(CONFIG_RESET_CONTROLLER)	+= reset.o
>>  obj-$(CONFIG_ARCH_HI3xxx)	+= clk-hi3620.o
>>  obj-$(CONFIG_ARCH_HIP04)	+= clk-hip04.o
>>  obj-$(CONFIG_ARCH_HIX5HD2)	+= clk-hix5hd2.o
>>  obj-$(CONFIG_COMMON_CLK_HI6220)	+= clk-hi6220.o
>>  obj-$(CONFIG_STUB_CLK_HI6220)	+= clk-hi6220-stub.o
>> +obj-$(CONFIG_COMMON_CLK_HI3519)	+= clk-hi3519.o
>> diff --git a/drivers/clk/hisilicon/clk-hi3519.c b/drivers/clk/hisilicon/clk-hi3519.c
>> new file mode 100644
>> index 0000000..e220234
>> --- /dev/null
>> +++ b/drivers/clk/hisilicon/clk-hi3519.c
>> @@ -0,0 +1,103 @@
>> +/*
>> + * Copyright (c) 2015 HiSilicon Technologies Co., Ltd.
>> + *
>> + * 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.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/of_address.h>
>> +#include <dt-bindings/clock/hi3519-clock.h>
>> +#include <linux/slab.h>
>> +#include <linux/delay.h>
>> +#include "clk.h"
>> +#include "reset.h"
>> +
>> +#define HI3519_FIXED_24M	(HI3519_EXT_CLKS + 1)
>> +#define HI3519_FIXED_50M	(HI3519_EXT_CLKS + 2)
>> +#define HI3519_FIXED_75M	(HI3519_EXT_CLKS + 3)
>> +#define HI3519_FIXED_125M	(HI3519_EXT_CLKS + 4)
>> +#define HI3519_FIXED_150M	(HI3519_EXT_CLKS + 5)
>> +#define HI3519_FIXED_200M	(HI3519_EXT_CLKS + 6)
>> +#define HI3519_FIXED_250M	(HI3519_EXT_CLKS + 7)
>> +#define HI3519_FIXED_300M	(HI3519_EXT_CLKS + 8)
>> +#define HI3519_FIXED_400M	(HI3519_EXT_CLKS + 9)
>> +#define HI3519_FMC_MUX		(HI3519_EXT_CLKS + 10)
>> +
>> +#define HI3519_NR_CLKS	128
>> +#define HI3519_NR_RSTS	128
>> +
>> +static struct hisi_fixed_rate_clock hi3519_fixed_rate_clks[] __initdata = {
>> +	{ HI3519_FIXED_3M, "3m", NULL, CLK_IS_ROOT, 3000000, },
>> +	{ HI3519_FIXED_24M, "24m", NULL, CLK_IS_ROOT, 24000000, },
>> +	{ HI3519_FIXED_50M, "50m", NULL, CLK_IS_ROOT, 50000000, },
>> +	{ HI3519_FIXED_75M, "75m", NULL, CLK_IS_ROOT, 75000000, },
>> +	{ HI3519_FIXED_125M, "125m", NULL, CLK_IS_ROOT, 125000000, },
>> +	{ HI3519_FIXED_150M, "150m", NULL, CLK_IS_ROOT, 150000000, },
>> +	{ HI3519_FIXED_200M, "200m", NULL, CLK_IS_ROOT, 200000000, },
>> +	{ HI3519_FIXED_250M, "250m", NULL, CLK_IS_ROOT, 250000000, },
>> +	{ HI3519_FIXED_300M, "300m", NULL, CLK_IS_ROOT, 300000000, },
>> +	{ HI3519_FIXED_400M, "400m", NULL, CLK_IS_ROOT, 400000000, },
>> +};
>> +
>> +static const char *fmc_mux_p[] __initconst = {
>> +		"24m", "75m", "125m", "150m", "200m", "250m", "300m", "400m", };
>> +static u32 fmc_mux_table[] = {0, 1, 2, 3, 4, 5, 6, 7};
>> +
>> +static struct hisi_mux_clock hi3519_mux_clks[] __initdata = {
>> +	{ HI3519_FMC_MUX, "fmc_mux", fmc_mux_p, ARRAY_SIZE(fmc_mux_p),
>> +		CLK_SET_RATE_PARENT, 0xc0, 2, 3, 0, fmc_mux_table, },
>> +};
>> +
>> +static struct hisi_gate_clock hi3519_gate_clks[] __initdata = {
>> +	/* fmc */
>> +	{ HI3519_FMC_CLK, "clk_fmc", "fmc_mux",
>> +		CLK_SET_RATE_PARENT, 0xc0, 1, 0, },
>> +	/* uart */
>> +	{ HI3519_UART0_CLK, "clk_uart0", "24m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 20, 0, },
>> +	{ HI3519_UART1_CLK, "clk_uart1", "24m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 21, 0, },
>> +	{ HI3519_UART2_CLK, "clk_uart2", "24m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 22, 0, },
>> +	{ HI3519_UART3_CLK, "clk_uart3", "24m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 23, 0, },
>> +	{ HI3519_UART4_CLK, "clk_uart4", "24m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 24, 0, },
>> +	{ HI3519_SPI0_CLK, "clk_spi0", "50m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 16, 0, },
>> +	{ HI3519_SPI1_CLK, "clk_spi1", "50m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 17, 0, },
>> +	{ HI3519_SPI2_CLK, "clk_spi2", "50m",
>> +		CLK_SET_RATE_PARENT, 0xe4, 18, 0, },
>> +};
>> +
>> +static void __init hi3519_clk_init(struct device_node *np)
>> +{
>> +	struct hisi_clock_data *clk_data;
>> +
>> +	clk_data = hisi_clk_init(np, HI3519_NR_CLKS);
>> +	if (!clk_data)
>> +		return;
>> +
>> +	hisi_reset_init(np, HI3519_NR_RSTS);
>> +
>> +	hisi_clk_register_fixed_rate(hi3519_fixed_rate_clks,
>> +				     ARRAY_SIZE(hi3519_fixed_rate_clks),
>> +				     clk_data);
>> +	hisi_clk_register_mux(hi3519_mux_clks, ARRAY_SIZE(hi3519_mux_clks),
>> +					clk_data);
>> +	hisi_clk_register_gate(hi3519_gate_clks,
>> +			ARRAY_SIZE(hi3519_gate_clks), clk_data);
>> +}
>> +
>> +CLK_OF_DECLARE(hi3519_clk, "hisilicon,hi3519-crg", hi3519_clk_init);
>> diff --git a/drivers/clk/hisilicon/reset.c b/drivers/clk/hisilicon/reset.c
>> new file mode 100644
>> index 0000000..cf5c32a
>> --- /dev/null
>> +++ b/drivers/clk/hisilicon/reset.c
>> @@ -0,0 +1,149 @@
>> +/*
>> + * Hisilicon Reset Controller driver
>> + *
>> + * Copyright (c) 2015 HiSilicon Technologies Co., Ltd.
>> + *
>> + * 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.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset-controller.h>
>> +#include <linux/slab.h>
>> +#include <linux/spinlock.h>
>> +#include <linux/types.h>
>> +
>> +#define	HISI_RESET_BIT_SHIFT	0
>> +#define	HISI_RESET_BIT_WIDTH	16
>> +#define	HISI_RESET_OFFSET_SHIFT	16
>> +#define	HISI_RESET_OFFSET_WIDTH	16
> 
> Maybe use #define HISI_RESET_OFFSET_MASK 0xffff0000 ?
> instead? Then you wouldn't need the (BIT(width)-1) dance below.
> 

It's better to use this instead. Thank you.

>> +
>> +struct hisi_reset_controller {
>> +	spinlock_t	lock;
>> +	void __iomem	*membase;
>> +	struct reset_controller_dev	rcdev;
>> +};
>> +
>> +
>> +#define to_hisi_reset_controller(rcdev)  \
>> +	container_of(rcdev, struct hisi_reset_controller, rcdev)
>> +
>> +/*31                        16                         0
>> + * |---reset_spec->args[0]---|---reset_spec->args[1]---|
>> + * |-------reg_offset--------|--------reg_bit----------|
>> + */
> 
> Note that the return value of of_xlate is signed, so BIT(31) has to be
> reserved for the sign bit. This is not going to be a problem in
> practice, but since you already calculate args[0] & offset_mask, you
> might as well make sure that BIT(31) is clear in the non-error case.
> 

OK.

For hi3519 soc, it's enough to reserve 5 bits for reg_bit and 16 bits for reg_offset.
BIT(31) can be reserved for the sign bit.

Thank you.

>> +static int hisi_reset_of_xlate(struct reset_controller_dev *rcdev,
>> +			const struct of_phandle_args *reset_spec)
>> +{
>> +	unsigned int offset, bit, id;
>> +	const __be32 *addr;
>> +	u64 size;
>> +
>> +	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
>> +		return -EINVAL;
>> +
>> +	addr = of_get_address(rcdev->of_node, 0, &size, NULL);
>> +	if (!addr)
>> +		return -EINVAL;
> 
> Why is this check needed?
> 
This is used to check the validity of the reg_offset and reg_bit.
The reg_offset value can't exceed the address range of the CRG block.
The reg_bit value can't exceed 32. If the bit width of reg_bit is limited to
5 and the bit width of reg_offset is limited to 16, this check can be removed.

>> +	if (reset_spec->args[1] >= 32
>> +		|| reset_spec->args[0] + reset_spec->args[1] / 8 > size)
>> +		return -EINVAL;
>> +
>> +	offset = reset_spec->args[0] & (BIT(HISI_RESET_OFFSET_WIDTH) - 1);
>> +	bit = (reset_spec->args[1] & (BIT(HISI_RESET_BIT_WIDTH) - 1));
>> +	id = offset << HISI_RESET_OFFSET_SHIFT | bit;
>> +
>> +	return id;
>> +}
>> +
>> +static int hisi_reset_assert(struct reset_controller_dev *rcdev,
>> +			      unsigned long id)
>> +{
>> +	struct hisi_reset_controller *rstc = to_hisi_reset_controller(rcdev);
>> +	unsigned int offset, bit;
>> +	unsigned long flags;
>> +	u32 reg;
>> +
>> +	offset = id >> HISI_RESET_OFFSET_SHIFT;
>> +	offset &= (BIT(HISI_RESET_OFFSET_WIDTH) - 1);
>> +	bit = id & (BIT(HISI_RESET_BIT_WIDTH) - 1);
>> +
>> +	spin_lock_irqsave(&rstc->lock, flags);
>> +
>> +	reg = readl(rstc->membase + offset);
>> +	writel(reg | BIT(bit), rstc->membase + offset);
>> +
>> +	spin_unlock_irqrestore(&rstc->lock, flags);
>> +
>> +	return 0;
>> +}
>> +
>> +static int hisi_reset_deassert(struct reset_controller_dev *rcdev,
>> +				unsigned long id)
>> +{
>> +	struct hisi_reset_controller *rstc = to_hisi_reset_controller(rcdev);
>> +	unsigned int offset, bit;
>> +	unsigned long flags;
>> +	u32 reg;
>> +
>> +	offset = id >> HISI_RESET_OFFSET_SHIFT;
>> +	offset &= (BIT(HISI_RESET_OFFSET_WIDTH) - 1);
>> +	bit = id & (BIT(HISI_RESET_BIT_WIDTH) - 1);
>> +
>> +	spin_lock_irqsave(&rstc->lock, flags);
>> +
>> +	reg = readl(rstc->membase + offset);
>> +	writel(reg & ~BIT(bit), rstc->membase + offset);
>> +
>> +	spin_unlock_irqrestore(&rstc->lock, flags);
>> +
>> +	return 0;
>> +}
>> +
>> +static struct reset_control_ops hisi_reset_ops = {
>> +	.assert		= hisi_reset_assert,
>> +	.deassert	= hisi_reset_deassert,
>> +};
>> +
>> +int __init hisi_reset_init(struct device_node *np,
>> +					     int nr_rsts)
>> +{
>> +	struct hisi_reset_controller *rstc;
>> +
>> +	rstc = kzalloc(sizeof(*rstc), GFP_KERNEL);
>> +	if (!rstc)
>> +		return -ENOMEM;
>> +
>> +	rstc->membase = of_iomap(np, 0);
>> +	if (!rstc->membase)
>> +		return -EINVAL;
>> +
>> +	spin_lock_init(&rstc->lock);
>> +
>> +	rstc->rcdev.owner = THIS_MODULE;
>> +	rstc->rcdev.nr_resets = nr_rsts;
> 
> nr_resets is only used by of_reset_simple_xlate to check whether a given
> id is valid. This check obviously doesn't help if your ids are sparse,
> so nr_resets serves no purpose if you don't use it in
> hisi_reset_of_xlate. Other drivers have set this to the max id plus one,
> for example sunxi or zynq.
> 

Yes, nr_resets is not used in hisi_reset_of_xlate. I will remove this argument.

Many thanks.

Jiancheng

>> +	rstc->rcdev.ops = &hisi_reset_ops;
>> +	rstc->rcdev.of_node = np;
>> +	rstc->rcdev.of_reset_n_cells = 2;
>> +	rstc->rcdev.of_xlate = hisi_reset_of_xlate;
>> +
>> +	return reset_controller_register(&rstc->rcdev);
>> +}
> [...]
> 
> regards
> Philipp
> 
> 
> .
> 

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