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Date: Wed, 4 Jul 2018 10:41:51 +0200
From: Neil Armstrong <narmstrong@...libre.com>
To: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc: khilman@...libre.com, linux-amlogic@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/3] soc: amlogic: Add Meson GX Clock Measure driver
Hi Martin,
On 03/07/2018 21:18, Martin Blumenstingl wrote:
> Hi Neil,
>
> On Tue, Jul 3, 2018 at 3:23 PM Neil Armstrong <narmstrong@...libre.com> wrote:
>>
>> The Amlogic Meson GX SoCs embeds a clock measurer IP to measure the internal
>> clock paths frequencies.
>> The precision is in the order of the MHz.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>> drivers/soc/amlogic/Kconfig | 8 ++
>> drivers/soc/amlogic/Makefile | 1 +
>> drivers/soc/amlogic/meson-gx-clk-measure.c | 224 +++++++++++++++++++++++++++++
>> 3 files changed, 233 insertions(+)
>> create mode 100644 drivers/soc/amlogic/meson-gx-clk-measure.c
>>
>> diff --git a/drivers/soc/amlogic/Kconfig b/drivers/soc/amlogic/Kconfig
>> index b04f6e4..4a3217d 100644
>> --- a/drivers/soc/amlogic/Kconfig
>> +++ b/drivers/soc/amlogic/Kconfig
>> @@ -1,5 +1,13 @@
>> menu "Amlogic SoC drivers"
>>
>> +config MESON_GX_CLK_MEASURE
>> + bool "Amlogic Meson GX SoC Clock Measure driver"
>> + depends on ARCH_MESON || COMPILE_TEST
>> + default ARCH_MESON
>> + help
>> + Say yes to support of Measuring a set of internal SoC clocks
>> + from the debugfs interface.
>> +
>> config MESON_GX_SOCINFO
>> bool "Amlogic Meson GX SoC Information driver"
>> depends on ARCH_MESON || COMPILE_TEST
>> diff --git a/drivers/soc/amlogic/Makefile b/drivers/soc/amlogic/Makefile
>> index 8fa3218..a0ad966 100644
>> --- a/drivers/soc/amlogic/Makefile
>> +++ b/drivers/soc/amlogic/Makefile
>> @@ -1,3 +1,4 @@
>> +obj-$(CONFIG_MESON_GX_CLK_MEASURE) += meson-gx-clk-measure.o
>> obj-$(CONFIG_MESON_GX_SOCINFO) += meson-gx-socinfo.o
>> obj-$(CONFIG_MESON_GX_PM_DOMAINS) += meson-gx-pwrc-vpu.o
>> obj-$(CONFIG_MESON_MX_SOCINFO) += meson-mx-socinfo.o
>> diff --git a/drivers/soc/amlogic/meson-gx-clk-measure.c b/drivers/soc/amlogic/meson-gx-clk-measure.c
>> new file mode 100644
>> index 0000000..434d9f3
>> --- /dev/null
>> +++ b/drivers/soc/amlogic/meson-gx-clk-measure.c
[...]
>> + CLK_MSR_ID(57, "wave420l_c"),
>> + CLK_MSR_ID(58, "wave420l_b"),
> AFAIK the Chips&Media WAVE420L video codec is only available on GXM (S912)
> I assume reading this on GXBB or GXL simply reads 0?
Yes
>
>> + CLK_MSR_ID(59, "hcodec"),
>> + CLK_MSR_ID(60, "alt_32k"),
>> + CLK_MSR_ID(61, "gpio_msr"),
>> + CLK_MSR_ID(62, "hevc"),
>> + CLK_MSR_ID(66, "vid_lock"),
>> + CLK_MSR_ID(70, "pwm_f"),
>> + CLK_MSR_ID(71, "pwm_e"),
>> + CLK_MSR_ID(72, "pwm_d"),
>> + CLK_MSR_ID(73, "pwm_C"),
> should this be pwm_c (instead of pwm_C)?
>
>> + CLK_MSR_ID(75, "aoclkx2_int"),
>> + CLK_MSR_ID(76, "aoclk_int"),
>> + CLK_MSR_ID(77, "rng_ring_osc_0"),
>> + CLK_MSR_ID(78, "rng_ring_osc_1"),
>> + CLK_MSR_ID(79, "rng_ring_osc_2"),
>> + CLK_MSR_ID(80, "rng_ring_osc_3"),
>> + CLK_MSR_ID(81, "vapb"),
>> + CLK_MSR_ID(82, "ge2d"),
>> +};
> I did a quick check whether the clock IDs are really the same for all GX SoCs:
> apart from clocks missing on older SoCs (see for example the WAVE420L
> clocks above) there were only minor renames but no conflicts!
I did the same work ! I will add this detail to the commit log.
Thanks for checking ;-)
>
>> +
>> +static int meson_gx_measure_id(struct meson_gx_msr *priv, unsigned int id)
>> +{
>> + unsigned int val;
>> + int ret;
>> +
>> + regmap_write(priv->regmap, MSR_CLK_REG0, 0);
>> +
>> + /* Set measurement gate to 50uS */
>> + regmap_update_bits(priv->regmap, MSR_CLK_REG0, MSR_CLK_DIV,
>> + FIELD_PREP(MSR_CLK_DIV, DIV_50US));
>> +
>> + /* Set ID */
>> + regmap_update_bits(priv->regmap, MSR_CLK_REG0, MSR_CLK_SRC,
>> + FIELD_PREP(MSR_CLK_SRC, id));
>> +
>> + /* Enable & Start */
>> + regmap_update_bits(priv->regmap, MSR_CLK_REG0,
>> + MSR_RUN | MSR_ENABLE,
>> + MSR_RUN | MSR_ENABLE);
>> +
>> + ret = regmap_read_poll_timeout(priv->regmap, MSR_CLK_REG0,
>> + val, !(val & MSR_BUSY), 10, 1000);
>> + if (ret)
>> + return ret;
>> +
>> + /* Disable */
>> + regmap_update_bits(priv->regmap, MSR_CLK_REG0, MSR_ENABLE, 0);
>> +
>> + /* Get the value in MHz*64 */
>> + regmap_read(priv->regmap, MSR_CLK_REG2, &val);
>> +
>> + return (((val + 31) & MSR_VAL_MASK) / 64) * 1000000;
>> +}
>> +
>> +static int clk_msr_show(struct seq_file *s, void *data)
>> +{
>> + struct meson_gx_msr_id *clk_msr_id = s->private;
>> + int val;
>> +
>> + val = meson_gx_measure_id(clk_msr_id->priv, clk_msr_id->id);
>> + if (val < 0)
>> + return val;
>> +
>> + seq_printf(s, "%d\n", val);
With jerome, we managed to have a much higher precision by cycling over the divider
and checking when the counter overflows. And I will print the precision in the clock debugfs
entry.
>> +
>> + return 0;
>> +}
>> +DEFINE_SHOW_ATTRIBUTE(clk_msr);
> have you considered modelling this as clock driver instead?
Yes, but it can wait.
Actually this clk-msr can be feed to GEN_CLK and be outputted to a pad,
but all this is only for debug, so we can stick to debugfs for now.
Question, should I separate the clocks in a subdirectory and add a summary file like
for the clk debugfs ?
/sys/kernel/debug/meson-clk-msr
------------------|--- summary
------------------|--- clks
-----------------------|--- ring_osc_out_ee_0
...
-----------------------|--- ge2d
?
>
>> +
>> +static const struct regmap_config clk_msr_regmap_config = {
>> + .reg_bits = 32,
>> + .val_bits = 32,
>> + .reg_stride = 4,
>> + .max_register = MSR_CLK_REG2,
>> +};
>> +
>> +static int meson_gx_msr_probe(struct platform_device *pdev)
>> +{
>> + struct meson_gx_msr *priv;
>> + struct resource *res;
>> + struct dentry *root;
>> + void __iomem *base;
>> + int i;
>> +
>> + priv = devm_kzalloc(&pdev->dev, sizeof(struct meson_gx_msr),
>> + GFP_KERNEL);
>> + if (!priv)
>> + return -ENOMEM;
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + base = devm_ioremap_resource(&pdev->dev, res);
>> + if (IS_ERR(base)) {
>> + dev_err(&pdev->dev, "io resource mapping failed\n");
>> + return PTR_ERR(base);
>> + }
>> +
>> + priv->regmap = devm_regmap_init_mmio(&pdev->dev, base,
>> + &clk_msr_regmap_config);
>> + if (IS_ERR(priv->regmap))
>> + return PTR_ERR(priv->regmap);
>> +
>> + root = debugfs_create_dir("meson-clk-msr", NULL);
>> +
>> + for (i = 0 ; i < CLK_MSR_MAX ; ++i) {
>> + if (!clk_msr[i].name)
>> + continue;
>> +
>> + clk_msr[i].priv = priv;
>> +
>> + debugfs_create_file(clk_msr[i].name, 0444, root,
>> + &clk_msr[i], &clk_msr_fops);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id meson_gx_msr_match_table[] = {
>> + { .compatible = "amlogic,meson-gx-clk-measure" },
> maybe pass the meson_gx_msr_id table here because it seems easy to add
> support for AXG and Meson8/Meson8b/Meson8m2 later on
Yes, I will rename the driver to be generic and pass the table as match data.
>
>
> Regards
> Martin
>
Thanks for reviewing !
Neil
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