Re: [PATCH v4 5/7] thermal: sun8i: add SRAM register access code

Jernej Škrabec
2024-02-15T21:25:13Z

Dne petek, 09. februar 2024 ob 15:42:19 CET je Andre Przywara napisal(a):
> The Allwinner H616 SoC needs to clear a bit in one register in the SRAM
> controller, to report reasonable temperature values. On reset, bit 16 in
> register 0x3000000 is set, which leads to the driver reporting
> temperatures around 200C. Clearing this bit brings the values down to the
> expected range. The BSP code does a one-time write in U-Boot, with a
> comment just mentioning the effect on the THS, but offering no further
> explanation.
>
> To not rely on firmware to set things up for us, add code that queries
> the SRAM controller device via a DT phandle link, then clear just this
> single bit.
>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
> drivers/thermal/sun8i_thermal.c | 50 +++++++++++++++++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/drivers/thermal/sun8i_thermal.c b/drivers/thermal/sun8i_thermal.c
> index c919b0fd5e169..8a9d2bdc71ece 100644
> --- a/drivers/thermal/sun8i_thermal.c
> +++ b/drivers/thermal/sun8i_thermal.c
> @@ -15,6 +15,7 @@
> #include <linux/module.h>
> #include <linux/nvmem-consumer.h>
> #include <linux/of.h>
> +#include <linux/of_platform.h>
> #include <linux/platform_device.h>
> #include <linux/regmap.h>
> #include <linux/reset.h>
> @@ -66,6 +67,7 @@ struct tsensor {
> struct ths_thermal_chip {
> bool has_mod_clk;
> bool has_bus_clk_reset;
> + bool needs_sram;
> int sensor_num;
> int offset;
> int scale;
> @@ -83,6 +85,7 @@ struct ths_device {
> const struct ths_thermal_chip *chip;
> struct device *dev;
> struct regmap *regmap;
> + struct regmap_field *sram_regmap_field;
> struct reset_control *reset;
> struct clk *bus_clk;
> struct clk *mod_clk;
> @@ -337,6 +340,34 @@ static void sun8i_ths_reset_control_assert(void *data)
> reset_control_assert(data);
> }
>
> +static struct regmap *sun8i_ths_get_sram_regmap(struct device_node *node)
> +{
> + struct device_node *sram_node;
> + struct platform_device *sram_pdev;
> + struct regmap *regmap = NULL;
> +
> + sram_node = of_parse_phandle(node, "allwinner,sram", 0);
> + if (!sram_node)
> + return ERR_PTR(-ENODEV);
> +
> + sram_pdev = of_find_device_by_node(sram_node);
> + if (!sram_pdev) {
> + /* platform device might not be probed yet */
> + regmap = ERR_PTR(-EPROBE_DEFER);
> + goto out_put_node;
> + }
> +
> + /* If no regmap is found then the other device driver is at fault */
> + regmap = dev_get_regmap(&sram_pdev->dev, NULL);
> + if (!regmap)
> + regmap = ERR_PTR(-EINVAL);
> +
> + platform_device_put(sram_pdev);
> +out_put_node:
> + of_node_put(sram_node);
> + return regmap;
> +}
> +
> static int sun8i_ths_resource_init(struct ths_device *tmdev)
> {
> struct device *dev = tmdev->dev;
> @@ -381,6 +412,21 @@ static int sun8i_ths_resource_init(struct ths_device *tmdev)
> if (ret)
> return ret;
>
> + if (tmdev->chip->needs_sram) {
> + const struct reg_field sun8i_sram_reg_field =
> + REG_FIELD(0x0, 16, 16);

What about global static constant for a field? Many drivers do so and code
would be simpler.

Best regards,
Jernej

> + struct regmap *regmap;
> +
> + regmap = sun8i_ths_get_sram_regmap(dev->of_node);
> + if (IS_ERR(regmap))
> + return PTR_ERR(regmap);
> + tmdev->sram_regmap_field = devm_regmap_field_alloc(dev,
> + regmap,
> + sun8i_sram_reg_field);
> + if (IS_ERR(tmdev->sram_regmap_field))
> + return PTR_ERR(tmdev->sram_regmap_field);
> + }
> +
> ret = sun8i_ths_calibrate(tmdev);
> if (ret)
> return ret;
> @@ -427,6 +473,10 @@ static int sun50i_h6_thermal_init(struct ths_device *tmdev)
> {
> int val;
>
> + /* The H616 needs to have a bit in the SRAM control register cleared. */
> + if (tmdev->sram_regmap_field)
> + regmap_field_write(tmdev->sram_regmap_field, 0);
> +
> /*
> * The manual recommends an overall sample frequency of 50 KHz (20us,
> * 480 cycles at 24 MHz), which provides plenty of time for both the
>