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Subject: Re: [PATCH 1/3] soc: amlogic: Add Meson GX Clock Measure driver
To:     khilman@baylibre.com
Cc:     linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <1530624110-4687-1-git-send-email-narmstrong@baylibre.com>
 <1530624110-4687-2-git-send-email-narmstrong@baylibre.com>
From:   Neil Armstrong <narmstrong@baylibre.com>
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Date:   Tue, 3 Jul 2018 16:31:56 +0200
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On 03/07/2018 15:21, Neil Armstrong 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.

The precision is more around 30Khz.

> 
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.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
> @@ -0,0 +1,224 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2017 BayLibre, SAS
> + * Author: Neil Armstrong <narmstrong@baylibre.com>
> + */
> +
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/bitfield.h>
> +#include <linux/seq_file.h>
> +#include <linux/debugfs.h>
> +#include <linux/regmap.h>
> +
> +#define MSR_CLK_DUTY		0x0
> +#define MSR_CLK_REG0		0x4
> +#define MSR_CLK_REG1		0x8
> +#define MSR_CLK_REG2		0xc
> +
> +#define MSR_CLK_DIV		GENMASK(15, 0)
> +#define MSR_ENABLE		BIT(16)
> +#define MSR_CONT		BIT(17) /* continuous measurement */
> +#define MSR_INTR		BIT(18) /* interrupts */
> +#define MSR_RUN			BIT(19)
> +#define MSR_CLK_SRC		GENMASK(26, 20)
> +#define MSR_BUSY		BIT(31)
> +
> +#define MSR_VAL_MASK		GENMASK(15, 0)
> +
> +#define DIV_50US		64
> +
> +#define CLK_MSR_MAX		128
> +
> +struct meson_gx_msr {
> +	struct regmap *regmap;
> +};
> +
> +struct meson_gx_msr_id {
> +	struct meson_gx_msr *priv;
> +	unsigned int id;
> +	const char *name;
> +};
> +
> +#define CLK_MSR_ID(__id, __name) \
> +	[__id] = {.id = __id, .name = __name,}
> +
> +static struct meson_gx_msr_id clk_msr[CLK_MSR_MAX] = {
> +	CLK_MSR_ID(0, "ring_osc_out_ee_0"),
> +	CLK_MSR_ID(1, "ring_osc_out_ee_1"),
> +	CLK_MSR_ID(2, "ring_osc_out_ee_2"),
> +	CLK_MSR_ID(3, "a53_ring_osc"),
> +	CLK_MSR_ID(4, "gp0_pll"),
> +	CLK_MSR_ID(6, "enci"),
> +	CLK_MSR_ID(7, "clk81"),
> +	CLK_MSR_ID(8, "encp"),
> +	CLK_MSR_ID(9, "encl"),
> +	CLK_MSR_ID(10, "vdac"),
> +	CLK_MSR_ID(11, "rgmii_tx"),
> +	CLK_MSR_ID(12, "pdm"),
> +	CLK_MSR_ID(13, "amclk"),
> +	CLK_MSR_ID(14, "fec_0"),
> +	CLK_MSR_ID(15, "fec_1"),
> +	CLK_MSR_ID(16, "fec_2"),
> +	CLK_MSR_ID(17, "sys_pll_div16"),
> +	CLK_MSR_ID(18, "sys_cpu_div16"),
> +	CLK_MSR_ID(19, "hdmitx_sys"),
> +	CLK_MSR_ID(20, "rtc_osc_out"),
> +	CLK_MSR_ID(21, "i2s_in_src0"),
> +	CLK_MSR_ID(22, "eth_phy_ref"),
> +	CLK_MSR_ID(23, "hdmi_todig"),
> +	CLK_MSR_ID(26, "sc_int"),
> +	CLK_MSR_ID(28, "sar_adc"),
> +	CLK_MSR_ID(31, "mpll_test_out"),
> +	CLK_MSR_ID(32, "vdec"),
> +	CLK_MSR_ID(35, "mali"),
> +	CLK_MSR_ID(36, "hdmi_tx_pixel"),
> +	CLK_MSR_ID(37, "i958"),
> +	CLK_MSR_ID(38, "vdin_meas"),
> +	CLK_MSR_ID(39, "pcm_sclk"),
> +	CLK_MSR_ID(40, "pcm_mclk"),
> +	CLK_MSR_ID(41, "eth_rx_or_rmii"),
> +	CLK_MSR_ID(42, "mp0_out"),
> +	CLK_MSR_ID(43, "fclk_div5"),
> +	CLK_MSR_ID(44, "pwm_b"),
> +	CLK_MSR_ID(45, "pwm_a"),
> +	CLK_MSR_ID(46, "vpu"),
> +	CLK_MSR_ID(47, "ddr_dpll_pt"),
> +	CLK_MSR_ID(48, "mp1_out"),
> +	CLK_MSR_ID(49, "mp2_out"),
> +	CLK_MSR_ID(50, "mp3_out"),
> +	CLK_MSR_ID(51, "nand_core"),
> +	CLK_MSR_ID(52, "sd_emmc_b"),
> +	CLK_MSR_ID(53, "sd_emmc_a"),
> +	CLK_MSR_ID(55, "vid_pll_div_out"),
> +	CLK_MSR_ID(56, "cci"),
> +	CLK_MSR_ID(57, "wave420l_c"),
> +	CLK_MSR_ID(58, "wave420l_b"),
> +	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"),
> +	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"),
> +};
> +
> +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));

Slight error, this should be DIV_50US - 1

> +
> +	/* 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;

And we can show the full calculation by pre-multiplying by 1000000 before dividing.

> +}
> +
> +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);
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(clk_msr);
> +
> +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" },
> +	{ /* sentinel */ }
> +};
> +
> +static struct platform_driver meson_gx_msr_driver = {
> +	.probe	= meson_gx_msr_probe,
> +	.driver = {
> +		.name		= "meson_gx_msr",
> +		.of_match_table	= meson_gx_msr_match_table,
> +	},
> +};
> +builtin_platform_driver(meson_gx_msr_driver);
>