linux-kernel - Re: [PATCH v8 2/3] firmware: scm: Modify only the download bits in TCSR register

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Date:   Wed, 25 Oct 2023 16:53:38 -0700
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Mukesh Ojha <quic_mojha@...cinc.com>, <agross@...nel.org>,
        <andersson@...nel.org>, <konrad.dybcio@...aro.org>,
        <linus.walleij@...aro.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-gpio@...r.kernel.org>,
        Poovendhan Selvaraj <quic_poovendh@...cinc.com>
Subject: Re: [PATCH v8 2/3] firmware: scm: Modify only the download bits in
 TCSR register



On 10/25/2023 5:05 AM, 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>
> ---
>  drivers/firmware/qcom/qcom_scm.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 25549178a30f..f1c4a9f9a53f 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>
> @@ -117,6 +119,10 @@ 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)
> +#define QCOM_DLOAD_FULLDUMP	0x1
> +#define QCOM_DLOAD_NODUMP	0x0
> +


Enum would be better here for related constants.

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index f1c4a9f9a53f..95f73a8c51d7 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -122,4 +122,6 @@ static const u8 qcom_scm_cpu_warm_bits[QCOM_SCM_BOOT_MAX_CPUS] = {
 #define QCOM_DLOAD_MASK                GENMASK(5, 4)
-#define QCOM_DLOAD_FULLDUMP    0x1
-#define QCOM_DLOAD_NODUMP      0x0
+enum qcom_dload_mode {
+       QCOM_DLOAD_NODUMP       = 0,
+       QCOM_DLOAD_FULLDUMP     = 1,
+};
 


>  static const char * const qcom_scm_convention_names[] = {
>  	[SMC_CONVENTION_UNKNOWN] = "unknown",
>  	[SMC_CONVENTION_ARM_32] = "smc arm 32",
> @@ -523,6 +529,7 @@ 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;
>  
> @@ -532,8 +539,9 @@ 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");

- Elliot