Re: [PATCH 3/3] clk: meson: add sub EMMC clock controller driver

[Yixun Lan]

Hi Martin


On 07/04/18 02:58, Martin Blumenstingl wrote:
> Hi Yixun,
> 
> apart from what Jerome found this looks good to me.
> one small "issue" and a question are inline below
> 
> On Tue, Jul 3, 2018 at 9:00 AM Yixun Lan <yixun.lan@xxxxxxxxxxx> wrote:
>>
>> This patch will add a EMMC clock controller driver support,
>> It provide a mux and divider clock.
>>
>> This clock driver can be protentially used by either EMMC and
>> NAND driver.
>>
>> Signed-off-by: Yixun Lan <yixun.lan@xxxxxxxxxxx>
>> ---
>>  drivers/clk/meson/Kconfig     |   9 +++
>>  drivers/clk/meson/Makefile    |   1 +
>>  drivers/clk/meson/emmc-clkc.c | 136 ++++++++++++++++++++++++++++++++++
>>  3 files changed, 146 insertions(+)
>>  create mode 100644 drivers/clk/meson/emmc-clkc.c
>>
>> diff --git a/drivers/clk/meson/Kconfig b/drivers/clk/meson/Kconfig
>> index efaa70f682b4..2f27ff08e4eb 100644
>> --- a/drivers/clk/meson/Kconfig
>> +++ b/drivers/clk/meson/Kconfig
>> @@ -15,6 +15,15 @@ config COMMON_CLK_MESON_AO
>>         select COMMON_CLK_REGMAP_MESON
>>         select RESET_CONTROLLER
>>
>> +config COMMON_CLK_EMMC_MESON
>> +       tristate "Meson EMMC Sub Clock Controller Driver"
>> +       depends on COMMON_CLK_AMLOGIC
>> +       select MFD_SYSCON
>> +       select REGMAP
>> +       help
>> +         Support for the EMMC sub clock controller on AmLogic Meson Platform,
>> +         Say Y if you want this clock enabled.
>> +
>>  config COMMON_CLK_REGMAP_MESON
>>         bool
>>         select REGMAP
>> diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
>> index 72ec8c40d848..2f04f77ba4de 100644
>> --- a/drivers/clk/meson/Makefile
>> +++ b/drivers/clk/meson/Makefile
>> @@ -9,4 +9,5 @@ obj-$(CONFIG_COMMON_CLK_MESON8B) += meson8b.o
>>  obj-$(CONFIG_COMMON_CLK_GXBB)   += gxbb.o gxbb-aoclk.o gxbb-aoclk-32k.o
>>  obj-$(CONFIG_COMMON_CLK_AXG)    += axg.o axg-aoclk.o
>>  obj-$(CONFIG_COMMON_CLK_AXG_AUDIO)     += axg-audio.o
>> +obj-$(CONFIG_COMMON_CLK_EMMC_MESON)    += emmc-clkc.o
>>  obj-$(CONFIG_COMMON_CLK_REGMAP_MESON)  += clk-regmap.o
>> diff --git a/drivers/clk/meson/emmc-clkc.c b/drivers/clk/meson/emmc-clkc.c
>> new file mode 100644
>> index 000000000000..cf5bb9f34327
>> --- /dev/null
>> +++ b/drivers/clk/meson/emmc-clkc.c
>> @@ -0,0 +1,136 @@
>> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>> +/*
>> + * Amlogic Meson EMMC Sub Clock Controller Driver
>> + *
>> + * Copyright (c) 2018 Amlogic, inc.
>> + * Author: Yixun Lan <yixun.lan@xxxxxxxxxxx>
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/clk-provider.h>
>> +#include <linux/init.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_device.h>
>> +#include <linux/mfd/syscon.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +
>> +#include <dt-bindings/clock/emmc-clkc.h>
>> +
>> +#include "clkc.h"
>> +
>> +#define SD_EMMC_CLOCK          0
>> +#define MUX_CLK_NUM_PARENTS    2
>> +#define EMMC_MAX_CLKS          2
>> +#define CLK_NAME_LEN           48
>> +
>> +static struct clk_regmap_mux_data emmc_clkc_mux_data = {
>> +       .offset = SD_EMMC_CLOCK,
>> +       .mask = 0x3,
>> +       .shift = 6,
>> +};
>> +
>> +static struct clk_regmap_div_data emmc_clkc_div_data = {
>> +       .offset = SD_EMMC_CLOCK,
>> +       .shift = 0,
>> +       .width = 6,
>> +       .flags = CLK_DIVIDER_ROUND_CLOSEST | CLK_DIVIDER_ONE_BASED,
>> +};
>> +
>> +static const struct of_device_id clkc_match_table[] = {
>> +       { .compatible = "amlogic,emmc-clkc" },
> shouldn't this be "amlogic,meson-axg-emmc-clkc" (and optionally also
> "amlogic,meson-gx-emmc-clkc")?
> 
sounds good to me..
is it a convention to always make the compatible specific ?..

>> +       {}
>> +};
>> +
>> +static int emmc_clkc_probe(struct platform_device *pdev)
>> +{
>> +       struct device *dev = &pdev->dev;
>> +       struct clk_regmap *mux, *div;
>> +       struct regmap *map;
>> +       struct clk *clk;
>> +       int i, ret;
>> +       const char *parent_names[MUX_CLK_NUM_PARENTS];
>> +       struct clk_init_data init;
>> +       char mux_name[CLK_NAME_LEN], div_name[CLK_NAME_LEN];
>> +       struct clk_hw_onecell_data *onecell_data;
>> +
>> +       map = syscon_node_to_regmap(dev->of_node);
>> +
>> +       mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
>> +       div = devm_kzalloc(dev, sizeof(*div), GFP_KERNEL);
>> +
>> +       onecell_data = devm_kzalloc(dev, sizeof(*onecell_data) +
>> +                                   sizeof(*onecell_data->hws) * EMMC_MAX_CLKS,
>> +                                   GFP_KERNEL);
>> +
>> +       if (!mux || !div || !onecell_data)
>> +               return -ENOMEM;
>> +
>> +       for (i = 0; i < MUX_CLK_NUM_PARENTS; i++) {
>> +               char name[8];
>> +
>> +               snprintf(name, sizeof(name), "clkin%d", i);
>> +               clk = devm_clk_get(dev, name);
>> +               if (IS_ERR(clk)) {
>> +                       if (clk != ERR_PTR(-EPROBE_DEFER))
>> +                               dev_err(dev, "Missing clock %s\n", name);
>> +                       return PTR_ERR(clk);
>> +               }
>> +
>> +               parent_names[i] = __clk_get_name(clk);
>> +       }
>> +
>> +       mux->map = map;
>> +       mux->data = &emmc_clkc_mux_data;
>> +
>> +       snprintf(mux_name, CLK_NAME_LEN, "%s#emmc_mux", dev_name(dev));
>> +
>> +       init.name = mux_name;
>> +       init.ops = &clk_regmap_mux_ops;
>> +       init.flags = CLK_SET_RATE_PARENT;
>> +       init.parent_names = parent_names;
>> +       init.num_parents = MUX_CLK_NUM_PARENTS;
>> +
>> +       mux->hw.init = &init;
>> +       ret = devm_clk_hw_register(dev, &mux->hw);
>> +       if (ret) {
>> +               dev_err(dev, "Mux clock registration failed\n");
>> +               return ret;
>> +       }
>> +
>> +       parent_names[0] = mux_name;
>> +       div->map = map;
>> +       div->data = &emmc_clkc_div_data;
>> +
>> +       snprintf(div_name, CLK_NAME_LEN, "%s#emmc_div", dev_name(dev));
>> +
>> +       init.name = div_name;
>> +       init.ops = &clk_regmap_divider_ops;
>> +       init.flags = CLK_SET_RATE_PARENT;
>> +       init.parent_names = parent_names;
>> +       init.num_parents = 1;
>> +
>> +       div->hw.init = &init;
>> +       ret = devm_clk_hw_register(dev, &div->hw);
>> +       if (ret) {
>> +               dev_err(dev, "Div clock registration failed\n");
>> +               return ret;
>> +       }
>> +
>> +       onecell_data->hws[CLKID_EMMC_C_MUX] = &mux->hw,
>> +       onecell_data->hws[CLKID_EMMC_C_DIV] = &div->hw,
>> +       onecell_data->num = EMMC_MAX_CLKS;
> you are describing the mux and the divider here
> however, meson-gx-mmc.c has a few more clock related bits:
> - CLK_CORE_PHASE_MASK
> - CLK_TX_PHASE_MASK
> - CLK_RX_PHASE_MASK
> - CLK_V2_TX_DELAY_MASK / CLK_V3_TX_DELAY_MASK
> - CLK_V2_RX_DELAY_MASK / CLK_V3_RX_DELAY_MASK
> - CLK_V2_ALWAYS_ON / CLK_V3_ALWAYS_ON
> 
> are these used for the MMC clock or are some of these routed to the
> NAND pins as well?

There clocks are not used in NAND driver..

I understand your concern here, if there clocks are also routed to NAND
pins, then we also need to implement them here
actually, to answer your question, I need to query the ASIC team..

> 
> 
> Regards
> Martin
> 
> .
>