Re: [PATCH v5 1/6] clk: hisilicon: add CRG driver for hi3519 soc

[xuejiancheng <xuejiancheng@huawei.com>]

Hi Mike,

On 2016/1/14 2:57, Michael Turquette wrote:
> Quoting xuejiancheng (2016-01-12 19:03:01)
>> Hi Stephen,
>>    Thank you very much for your reply.
>>
>> On 2016/1/13 6:12, Stephen Boyd wrote:
>>> On 01/08, Jiancheng Xue wrote:
>>>> 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"
>>>
>>> It looks like this has to be bool. Otherwise it needs to be a
>>> platform driver and the hisilicon APIs need to be exported and
>>> lose their __init markings.
>>>
>> Yes,it's a problem. I will fix it in next version. Thank you.
> 
> The best solution would be to make this clock driver a real platform
> driver.
> 
Now the work clock of the clocksource timer-sp804 is provided by this driver. So
it need to be registered early by CLK_OF_DECLARE. If the timer clock is treated
as a fixed-clock provider, this driver can be implemented as a platform driver.
Then the crg device must be registered before other clock consumer devices.Accordingly
the crg device node must be written above all other clock consumer devices node in dts files.
I think it is also a dependence.

Can you help me understand why it is better to make this driver a platform driver?
Thank you very much!

> Regards,
> Mike
> 
>>
>>>> +    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/clk-hi3519.c b/drivers/clk/hisilicon/clk-hi3519.c
>>>> new file mode 100644
>>>> index 0000000..72d3a7b0
>>>> --- /dev/null
>>>> +++ b/drivers/clk/hisilicon/clk-hi3519.c
>>>> @@ -0,0 +1,105 @@
>>>> +
>>>> +#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
>>>
>>> Is this the same clock provider as the external clocks? I don't
>>> understand why we're offsetting the clock numbering if we have
>>> different providers. And if these are truly fixed clocks (except
>>> for the mux) perhaps they're not even provided by this hardware
>>> block, and are clocks that come from the board? If that's true
>>> then I would expect them to be described in DT as fixed rate
>>> clocks.
>>>
>> External clocks mentioned here are used directly as work clocks of other modules.
>> Clocks defined in this file (internal clocks) are used as parents of external
>> clocks. Internal clocks won't be referred by dts files and are just used in this driver.
>> So they are moved here from the header file.
>>
>> External clocks and internal clocks are all generated by this CRG block. The input clock
>> of the CRG block is always connected to a crystal oscillator on the board. So only one
>> clock provider is defined here.
>>
>> Some clocks generated by CRG won't change their rate during the system running. These clocks
>> are treated as fixed clocks here.
>>
>>>> +
>>>> +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 = {
>>>
>>> const char * const ?
>>>
>>
>> OK.
>>
>>>> +            "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 = {
>>>
>>> We should look into making these things const.
>>>
>> OK. I'll add this in next version.
>>
>>>> +    /* 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_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);
>>>> +
>>>> +    hisi_reset_init(np);
>>>> +}
>>>> +
>>>> +CLK_OF_DECLARE(hi3519_clk, "hisilicon,hi3519-crg", hi3519_clk_init);
>>>> diff --git a/drivers/clk/hisilicon/reset.h b/drivers/clk/hisilicon/reset.h
>>>> new file mode 100644
>>>> index 0000000..37856089
>>>> --- /dev/null
>>>> +++ b/drivers/clk/hisilicon/reset.h
>>>> @@ -0,0 +1,32 @@
>>>> +/*
>>>> + * 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/>.
>>>> + */
>>>> +
>>>> +#ifndef     __HISI_RESET_H
>>>> +#define     __HISI_RESET_H
>>>> +
>>>> +#include <linux/of.h>
>>>
>>> Drop this include and forward declare struct device_node instead.
>>>
>>
>> OK.
>>
>>>> +
>>>> +#ifdef CONFIG_RESET_CONTROLLER
>>>> +int __init hisi_reset_init(struct device_node *np);
>>>
>>> We don't need __init in header files.
>>>
>> OK. I'll remove it. Thank you.
>>
>> Jiancheng
>> .
>>
> 
> .
>