Re: [PATCH v2 2/2] phy: amlogic: Add a new driver for the HDMI TX PHY on Meson8/8b/8m2

Vinod Koul
2021-07-20T08:37:23Z

On 29-06-21, 20:20, Martin Blumenstingl wrote:
> Amlogic Meson8/8b/8m2 have a built-in HDMI PHY in the HHI register
> region. Unfortunately only few register bits are documented. For
> HHI_HDMI_PHY_CNTL0 the magic numbers are taken from the 3.10 vendor
> kernel.
>
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---
> drivers/phy/amlogic/Kconfig | 10 ++
> drivers/phy/amlogic/Makefile | 1 +
> drivers/phy/amlogic/phy-meson8-hdmi-tx.c | 162 +++++++++++++++++++++++
> 3 files changed, 173 insertions(+)
> create mode 100644 drivers/phy/amlogic/phy-meson8-hdmi-tx.c
>
> diff --git a/drivers/phy/amlogic/Kconfig b/drivers/phy/amlogic/Kconfig
> index db5d0cd757e3..486ca23aba32 100644
> --- a/drivers/phy/amlogic/Kconfig
> +++ b/drivers/phy/amlogic/Kconfig
> @@ -2,6 +2,16 @@
> #
> # Phy drivers for Amlogic platforms
> #
> +config PHY_MESON8_HDMI_TX
> + tristate "Meson8, Meson8b and Meson8m2 HDMI TX PHY driver"
> + depends on (ARCH_MESON && ARM) || COMPILE_TEST
> + depends on OF
> + select MFD_SYSCON
> + help
> + Enable this to support the HDMI TX PHYs found in Meson8,
> + Meson8b and Meson8m2 SoCs.
> + If unsure, say N.
> +
> config PHY_MESON8B_USB2
> tristate "Meson8, Meson8b, Meson8m2 and GXBB USB2 PHY driver"
> default ARCH_MESON
> diff --git a/drivers/phy/amlogic/Makefile b/drivers/phy/amlogic/Makefile
> index 8fa07fbd0d92..c0886c850bb0 100644
> --- a/drivers/phy/amlogic/Makefile
> +++ b/drivers/phy/amlogic/Makefile
> @@ -1,4 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_PHY_MESON8_HDMI_TX) += phy-meson8-hdmi-tx.o
> obj-$(CONFIG_PHY_MESON8B_USB2) += phy-meson8b-usb2.o
> obj-$(CONFIG_PHY_MESON_GXL_USB2) += phy-meson-gxl-usb2.o
> obj-$(CONFIG_PHY_MESON_G12A_USB2) += phy-meson-g12a-usb2.o
> diff --git a/drivers/phy/amlogic/phy-meson8-hdmi-tx.c b/drivers/phy/amlogic/phy-meson8-hdmi-tx.c
> new file mode 100644
> index 000000000000..ba5a4de54811
> --- /dev/null
> +++ b/drivers/phy/amlogic/phy-meson8-hdmi-tx.c
> @@ -0,0 +1,162 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Meson8, Meson8b and Meson8m2 HDMI TX PHY.
> + *
> + * Copyright (C) 2021 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/clk.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/phy/phy.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +
> +#define HHI_HDMI_PHY_CNTL0 0x0
> + #define HHI_HDMI_PHY_CNTL0_HDMI_CTL1 GENMASK(31, 16)
> + #define HHI_HDMI_PHY_CNTL0_HDMI_CTL0 GENMASK(15, 0)
> +
> +#define HHI_HDMI_PHY_CNTL1 0x4
> + #define HHI_HDMI_PHY_CNTL1_CLOCK_ENABLE BIT(1)
> + #define HHI_HDMI_PHY_CNTL1_SOFT_RESET BIT(0)
> +
> +#define HHI_HDMI_PHY_CNTL2 0x8
> +
> +struct phy_meson8_hdmi_tx_priv {
> + struct regmap *hhi;
> + struct clk *tmds_clk;
> + unsigned int reg_offset;
> +};
> +
> +static int phy_meson8_hdmi_tx_init(struct phy *phy)
> +{
> + struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
> +
> + return clk_prepare_enable(priv->tmds_clk);
> +}
> +
> +static int phy_meson8_hdmi_tx_exit(struct phy *phy)
> +{
> + struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
> +
> + clk_disable_unprepare(priv->tmds_clk);
> +
> + return 0;
> +}
> +
> +static int phy_meson8_hdmi_tx_power_on(struct phy *phy)
> +{
> + struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
> + unsigned int i;
> + u16 hdmi_ctl0;
> +
> + if (clk_get_rate(priv->tmds_clk) >= 2970UL * 1000 * 1000)
> + hdmi_ctl0 = 0x1e8b;
> + else
> + hdmi_ctl0 = 0x4d0b;

magic numbers..? I guess these are register offsets, would be better to
define..

> +
> + regmap_write(priv->hhi, priv->reg_offset + HHI_HDMI_PHY_CNTL0,
> + FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL1, 0x08c3) |
> + FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL0, hdmi_ctl0));
> +
> + regmap_write(priv->hhi, priv->reg_offset + HHI_HDMI_PHY_CNTL1, 0x0);
> +
> + /* Reset three times, just like the vendor driver does */
> + for (i = 0; i < 3; i++) {
> + regmap_write(priv->hhi, priv->reg_offset + HHI_HDMI_PHY_CNTL1,
> + HHI_HDMI_PHY_CNTL1_CLOCK_ENABLE |
> + HHI_HDMI_PHY_CNTL1_SOFT_RESET);
> + usleep_range(1000, 2000);
> +
> + regmap_write(priv->hhi, priv->reg_offset + HHI_HDMI_PHY_CNTL1,
> + HHI_HDMI_PHY_CNTL1_CLOCK_ENABLE);
> + usleep_range(1000, 2000);
> + }
> +
> + return 0;
> +}
> +
> +static int phy_meson8_hdmi_tx_power_off(struct phy *phy)
> +{
> + struct phy_meson8_hdmi_tx_priv *priv = phy_get_drvdata(phy);
> +
> + regmap_write(priv->hhi, priv->reg_offset + HHI_HDMI_PHY_CNTL0,
> + FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL1, 0x0841) |
> + FIELD_PREP(HHI_HDMI_PHY_CNTL0_HDMI_CTL0, 0x8d00));

more magic..

> +
> + return 0;
> +}
> +
> +static const struct phy_ops phy_meson8_hdmi_tx_ops = {
> + .init = phy_meson8_hdmi_tx_init,
> + .exit = phy_meson8_hdmi_tx_exit,
> + .power_on = phy_meson8_hdmi_tx_power_on,
> + .power_off = phy_meson8_hdmi_tx_power_off,
> + .owner = THIS_MODULE,
> +};
> +
> +static int phy_meson8_hdmi_tx_probe(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + struct phy_meson8_hdmi_tx_priv *priv;
> + struct phy_provider *phy_provider;
> + struct phy *phy;
> + u32 reg[2];
> + int ret;
> +
> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> +
> + ret = device_property_read_u32_array(&pdev->dev, "reg", reg,
> + ARRAY_SIZE(reg));

we have reg as single property, why array with 2 entries here?

> + if (ret)
> + return dev_err_probe(&pdev->dev, ret,
> + "Failed to parse the 'reg' property\n");
> +
> + priv->reg_offset = reg[0];

and mystery deepens, no use of reg[1], leftover artifacts?

> +
> + priv->hhi = syscon_node_to_regmap(np->parent);
> + if (IS_ERR(priv->hhi))
> + return PTR_ERR(priv->hhi);
> +
> + priv->tmds_clk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(priv->tmds_clk))
> + return PTR_ERR(priv->tmds_clk);
> +
> + phy = devm_phy_create(&pdev->dev, np, &phy_meson8_hdmi_tx_ops);
> + if (IS_ERR(phy))
> + return PTR_ERR(phy);
> +
> + phy_set_drvdata(phy, priv);
> +
> + phy_provider = devm_of_phy_provider_register(&pdev->dev,
> + of_phy_simple_xlate);
> +
> + return PTR_ERR_OR_ZERO(phy_provider);
> +}
> +
> +static const struct of_device_id phy_meson8_hdmi_tx_of_match[] = {
> + { .compatible = "amlogic,meson8-hdmi-tx-phy" },
> + { .compatible = "amlogic,meson8b-hdmi-tx-phy" },
> + { .compatible = "amlogic,meson8m2-hdmi-tx-phy" },
> + { /* sentinel */ }

I see that all three are handled similarly, no difference!

Maybe also add a amlogic,meson8-hdmi compatible and use that?

--
~Vinod