Re: [PATCH 2/2] hwrng: msm: add ACPI support

[Vinod <vkoul@kernel.org>]

On 21-06-18, 10:17, Timur Tabi wrote:
> Add support for probing on ACPI systems, with ACPI HID QCOM8160.
> 
> On ACPI systems, clocks are always enabled, the PRNG should
> already be enabled, and the register region is read-only.
> The driver only verifies that the hardware is already
> enabled never tries to disable or configure it.

so if you are using v2 hardware, are you pointing to High Level OS EE or
some other..?

> Signed-off-by: Timur Tabi <timur@codeaurora.org>
> ---
>  drivers/char/hw_random/msm-rng.c | 40 ++++++++++++++++++++++++++++++++++------
>  1 file changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/char/hw_random/msm-rng.c b/drivers/char/hw_random/msm-rng.c
> index 44580588b938..f34713d23d77 100644
> --- a/drivers/char/hw_random/msm-rng.c
> +++ b/drivers/char/hw_random/msm-rng.c
> @@ -20,6 +20,7 @@
>  #include <linux/of.h>
>  #include <linux/platform_device.h>
>  #include <linux/spinlock.h>
> +#include <linux/acpi.h>
>  
>  /* Device specific register offsets */
>  #define PRNG_DATA_OUT		0x0000
> @@ -186,16 +187,32 @@ static int msm_rng_probe(struct platform_device *pdev)
>  	if (IS_ERR(rng->base))
>  		return PTR_ERR(rng->base);
>  
> -	rng->clk = devm_clk_get(&pdev->dev, "core");
> -	if (IS_ERR(rng->clk))
> -		return PTR_ERR(rng->clk);
> -
>  	rng->hwrng.name = KBUILD_MODNAME;
> -	rng->hwrng.init = msm_rng_init;
> -	rng->hwrng.cleanup = msm_rng_cleanup;
>  	rng->hwrng.read = msm_rng_read;
>  	spin_lock_init(&rng->lock);
>  
> +	/*
> +	 * ACPI systems have v2 hardware. The clocks are always enabled,
> +	 * the PRNG register space is read-only, and the PRNG should
> +	 * already be enabled.
> +	 */
> +	if (has_acpi_companion(&pdev->dev)) {
> +		u32 val;
> +
> +		val = readl(rng->base + PRNG_CONFIG);

v2 EEs dont seem to have CONFIG register, so not sure about this one

> +		if (!(val & PRNG_CONFIG_HW_ENABLE)) {
> +			dev_err(&pdev->dev, "device is not enabled\n");
> +			return -ENODEV;
> +		}
> +	} else {
> +		rng->clk = devm_clk_get(&pdev->dev, "core");
> +		if (IS_ERR(rng->clk))
> +			return PTR_ERR(rng->clk);
> +
> +		rng->hwrng.init = msm_rng_init;
> +		rng->hwrng.cleanup = msm_rng_cleanup;
> +	}
> +
>  	ret = devm_hwrng_register(&pdev->dev, &rng->hwrng);
>  	if (ret) {
>  		dev_err(&pdev->dev, "failed to register hwrng\n");
> @@ -211,11 +228,22 @@ static int msm_rng_probe(struct platform_device *pdev)
>  };
>  MODULE_DEVICE_TABLE(of, msm_rng_of_match);
>  
> +#if IS_ENABLED(CONFIG_ACPI)
> +static const struct acpi_device_id msm_rng_acpi_match[] = {
> +	{
> +		.id = "QCOM8160",	/* v2 PRNG */
> +	},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(acpi, msm_rng_acpi_match);
> +#endif
> +
>  static struct platform_driver msm_rng_driver = {
>  	.probe = msm_rng_probe,
>  	.driver = {
>  		.name = KBUILD_MODNAME,
>  		.of_match_table = of_match_ptr(msm_rng_of_match),
> +		.acpi_match_table = ACPI_PTR(msm_rng_acpi_match),
>  	}
>  };
>  module_platform_driver(msm_rng_driver);
> -- 
> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
> Technologies, Inc.  Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.

-- 
~Vinod