linux-kernel - Re: [PATCH v12 3/9] firmware: qcom: scm: Modify only the download bits in TCSR register

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Date: Sat, 2 Mar 2024 13:13:31 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Mukesh Ojha <quic_mojha@...cinc.com>
Cc: konrad.dybcio@...aro.org, linux-arm-msm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linus.walleij@...aro.org, linux-gpio@...r.kernel.org, 
	Poovendhan Selvaraj <quic_poovendh@...cinc.com>, Kathiravan Thirumoorthy <quic_kathirav@...cinc.com>, 
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Elliot Berman <quic_eberman@...cinc.com>
Subject: Re: [PATCH v12 3/9] firmware: qcom: scm: Modify only the download
 bits in TCSR register

On Tue, Feb 27, 2024 at 09:23:02PM +0530, Mukesh Ojha wrote:
> Crashdump collection is done based on DLOAD bits of TCSR register.
> To retain other bits, scm driver need to read the register and
> modify only the DLOAD bits, as other bits in TCSR may have their
> own significance.
> 
> Co-developed-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
> Signed-off-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
> Tested-by: Kathiravan Thirumoorthy <quic_kathirav@...cinc.com> # IPQ9574 and IPQ5332
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Reviewed-by: Elliot Berman <quic_eberman@...cinc.com>
> ---
>  drivers/firmware/qcom/qcom_scm.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 8f766fce5f7c..bd6bfdf2d828 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -4,6 +4,8 @@
>   */
>  
>  #include <linux/arm-smccc.h>
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
>  #include <linux/clk.h>
>  #include <linux/completion.h>
>  #include <linux/cpumask.h>
> @@ -114,6 +116,12 @@ static const u8 qcom_scm_cpu_warm_bits[QCOM_SCM_BOOT_MAX_CPUS] = {
>  #define QCOM_SMC_WAITQ_FLAG_WAKE_ONE	BIT(0)
>  #define QCOM_SMC_WAITQ_FLAG_WAKE_ALL	BIT(1)
>  
> +#define QCOM_DLOAD_MASK		GENMASK(5, 4)
> +enum qcom_dload_mode {
> +	QCOM_DLOAD_NODUMP	= 0,
> +	QCOM_DLOAD_FULLDUMP	= 1,

These values are not enumerations, they represent fixed/defined values
in the interface. As such it's appropriate to use #define.

Regards,
Bjorn

> +};
> +
>  static const char * const qcom_scm_convention_names[] = {
>  	[SMC_CONVENTION_UNKNOWN] = "unknown",
>  	[SMC_CONVENTION_ARM_32] = "smc arm 32",
> @@ -531,6 +539,7 @@ static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
>  
>  static void qcom_scm_set_download_mode(bool enable)
>  {
> +	u32 val = enable ? QCOM_DLOAD_FULLDUMP : QCOM_DLOAD_NODUMP;
>  	bool avail;
>  	int ret = 0;
>  
> @@ -540,8 +549,9 @@ static void qcom_scm_set_download_mode(bool enable)
>  	if (avail) {
>  		ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
>  	} else if (__scm->dload_mode_addr) {
> -		ret = qcom_scm_io_writel(__scm->dload_mode_addr,
> -				enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
> +		ret = qcom_scm_io_rmw(__scm->dload_mode_addr,
> +				      QCOM_DLOAD_MASK,
> +				      FIELD_PREP(QCOM_DLOAD_MASK, val));
>  	} else {
>  		dev_err(__scm->dev,
>  			"No available mechanism for setting download mode\n");
> -- 
> 2.43.0.254.ga26002b62827
>