linux-kernel - [PATCH 2/4] firmware: scm: Modify only the DLOAD bit in TCSR register for download mode

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Message-ID: <1676990381-18184-3-git-send-email-quic_mojha@quicinc.com>
Date:   Tue, 21 Feb 2023 20:09:39 +0530
From:   Mukesh Ojha <quic_mojha@...cinc.com>
To:     <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Mukesh Ojha" <quic_mojha@...cinc.com>
Subject: [PATCH 2/4] firmware: scm: Modify only the DLOAD bit in TCSR register for download mode

CrashDump collection is based on the DLOAD bit of TCSR register.
To retain other bits, we read the register and modify only the DLOAD bit as
the other bits have their own significance.

Originally-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
---
 drivers/firmware/qcom_scm.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 51eb853..c376ba8 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -419,6 +419,7 @@ static void qcom_scm_set_download_mode(bool enable)
 {
 	bool avail;
 	int ret = 0;
+	u32 dload_addr_val;
 
 	avail = __qcom_scm_is_call_available(__scm->dev,
 					     QCOM_SCM_SVC_BOOT,
@@ -426,8 +427,16 @@ 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_readl(__scm->dload_mode_addr, &dload_addr_val);
+		if (ret) {
+			dev_err(__scm->dev,
+				"failed to read dload mode address value: %d\n", ret);
+			return;
+		}
+
+		ret = qcom_scm_io_writel(__scm->dload_mode_addr, enable ?
+				dload_addr_val | QCOM_SCM_BOOT_SET_DLOAD_MODE :
+				dload_addr_val & ~(QCOM_SCM_BOOT_SET_DLOAD_MODE));
 	} else {
 		dev_err(__scm->dev,
 			"No available mechanism for setting download mode\n");
-- 
2.7.4