linux-kernel - [PATCH] usb: phy: qusb: Use scm call to update value in register

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Date:   Thu, 15 Sep 2022 19:17:07 +0530
From:   Hiren Gohel <quic_vhiren@...cinc.com>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        <linux-kernel@...r.kernel.org>
CC:     Udipto Goswami <quic_ugoswami@...cinc.com>,
        Pratham Pratap <quic_ppratap@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>,
        Hiren Gohel <quic_vhiren@...cinc.com>
Subject: [PATCH] usb: phy: qusb: Use scm call to update value in register

Registers used by vendors to control any functionality could be
implemented by making the register secured. In such cases the
register cannot be updated with a new value since the normal
write ops will fail.

Hence, use the scm_call to do a secure write to the register.

Signed-off-by: Hiren Gohel <quic_vhiren@...cinc.com>
---
 drivers/firmware/qcom_scm.c | 19 +++++++++++++++++++
 drivers/firmware/qcom_scm.h |  1 +
 include/linux/qcom_scm.h    |  2 ++
 3 files changed, 22 insertions(+)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index cdbfe54..7131df8 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -400,6 +400,25 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
 }
 EXPORT_SYMBOL(qcom_scm_set_remote_state);
 
+void qcom_scm_phy_update_scm_level_shifter(u32 val)
+{
+	int ret;
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_BOOT,
+		.cmd = QCOM_SCM_QUSB2PHY_LVL_SHIFTER_CMD_ID,
+		.owner = ARM_SMCCC_OWNER_SIP
+	};
+
+	desc.args[0] = val;
+	desc.args[1] = 0;
+	desc.arginfo = QCOM_SCM_ARGS(2);
+
+	ret = qcom_scm_call(__scm->dev, &desc, NULL);
+	if (ret)
+		pr_err("Failed to update scm level shifter=0x%x\n", ret);
+}
+EXPORT_SYMBOL(qcom_scm_phy_update_scm_level_shifter);
+
 static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
 {
 	struct qcom_scm_desc desc = {
diff --git a/drivers/firmware/qcom_scm.h b/drivers/firmware/qcom_scm.h
index 0d51eef..0a8c25b 100644
--- a/drivers/firmware/qcom_scm.h
+++ b/drivers/firmware/qcom_scm.h
@@ -81,6 +81,7 @@ extern int scm_legacy_call(struct device *dev, const struct qcom_scm_desc *desc,
 #define QCOM_SCM_BOOT_SET_ADDR_MC	0x11
 #define QCOM_SCM_BOOT_SET_REMOTE_STATE	0x0a
 #define QCOM_SCM_FLUSH_FLAG_MASK	0x3
+#define QCOM_SCM_QUSB2PHY_LVL_SHIFTER_CMD_ID	0x1B
 #define QCOM_SCM_BOOT_MAX_CPUS		4
 #define QCOM_SCM_BOOT_MC_FLAG_AARCH64	BIT(0)
 #define QCOM_SCM_BOOT_MC_FLAG_COLDBOOT	BIT(1)
diff --git a/include/linux/qcom_scm.h b/include/linux/qcom_scm.h
index f8335644..3e5cbe9 100644
--- a/include/linux/qcom_scm.h
+++ b/include/linux/qcom_scm.h
@@ -124,4 +124,6 @@ extern int qcom_scm_lmh_dcvsh(u32 payload_fn, u32 payload_reg, u32 payload_val,
 extern int qcom_scm_lmh_profile_change(u32 profile_id);
 extern bool qcom_scm_lmh_dcvsh_available(void);
 
+extern void qcom_scm_phy_update_scm_level_shifter(u32 val);
+
 #endif
-- 
2.7.4