firmware: qcom: scm: Expose PAS command 10 as reset-controller

PAS command 10 is used to assert and deassert the MSS reset via
TrustZone, expose this as a reset-controller to mimic the direct
access case.

Cc: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>

drivers/firmware/Kconfig

@@ -184,6 +184,7 @@ config FW_CFG_SYSFS_CMDLINE
 config QCOM_SCM
 	bool
 	depends on ARM || ARM64
+	select RESET_CONTROLLER
 
 config QCOM_SCM_32
 	def_bool y

drivers/firmware/qcom_scm-32.c

@@ -547,3 +547,16 @@ int __qcom_scm_pas_shutdown(struct device *dev, u32 peripheral)
 
 	return ret ? : le32_to_cpu(out);
 }
+
+int __qcom_scm_pas_mss_reset(struct device *dev, bool reset)
+{
+	__le32 out;
+	__le32 in = cpu_to_le32(reset);
+	int ret;
+
+	ret = qcom_scm_call(dev, QCOM_SCM_SVC_PIL, QCOM_SCM_PAS_MSS_RESET,
+			&in, sizeof(in),
+			&out, sizeof(out));
+
+	return ret ? : le32_to_cpu(out);
+}

drivers/firmware/qcom_scm-64.c

@@ -342,3 +342,19 @@ int __qcom_scm_pas_shutdown(struct device *dev, u32 peripheral)
 
 	return ret ? : res.a1;
 }
+
+int __qcom_scm_pas_mss_reset(struct device *dev, bool reset)
+{
+	struct qcom_scm_desc desc = {0};
+	struct arm_smccc_res res;
+	int ret;
+
+	desc.args[0] = reset;
+	desc.args[1] = 0;
+	desc.arginfo = QCOM_SCM_ARGS(2);
+
+	ret = qcom_scm_call(dev, QCOM_SCM_SVC_PIL, QCOM_SCM_PAS_MSS_RESET, &desc,
+			    &res);
+
+	return ret ? : res.a1;
+}

drivers/firmware/qcom_scm.c

@@ -21,6 +21,7 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/clk.h>
+#include <linux/reset-controller.h>
 
 #include "qcom_scm.h"
 
@@ -29,6 +30,7 @@ struct qcom_scm {
 	struct clk *core_clk;
 	struct clk *iface_clk;
 	struct clk *bus_clk;
+	struct reset_controller_dev reset;
 };
 
 static struct qcom_scm *__scm;
@@ -283,6 +285,30 @@ int qcom_scm_pas_shutdown(u32 peripheral)
 }
 EXPORT_SYMBOL(qcom_scm_pas_shutdown);
 
+static int qcom_scm_pas_reset_assert(struct reset_controller_dev *rcdev,
+				     unsigned long idx)
+{
+	if (idx != 0)
+		return -EINVAL;
+
+	return __qcom_scm_pas_mss_reset(__scm->dev, 1);
+}
+
+static int qcom_scm_pas_reset_deassert(struct reset_controller_dev *rcdev,
+				       unsigned long idx)
+{
+	if (idx != 0)
+		return -EINVAL;
+
+	return __qcom_scm_pas_mss_reset(__scm->dev, 0);
+}
+
+static const struct reset_control_ops qcom_scm_pas_reset_ops = {
+	.assert = qcom_scm_pas_reset_assert,
+	.deassert = qcom_scm_pas_reset_deassert,
+};
+
+
 static int qcom_scm_probe(struct platform_device *pdev)
 {
 	struct qcom_scm *scm;
@@ -316,6 +342,11 @@ static int qcom_scm_probe(struct platform_device *pdev)
 		}
 	}
 
+	scm->reset.ops = &qcom_scm_pas_reset_ops;
+	scm->reset.nr_resets = 1;
+	scm->reset.of_node = pdev->dev.of_node;
+	reset_controller_register(&scm->reset);
+
 	/* vote for max clk rate for highest performance */
 	ret = clk_set_rate(scm->core_clk, INT_MAX);
 	if (ret)

drivers/firmware/qcom_scm.h

@@ -46,6 +46,7 @@ extern void __qcom_scm_init(void);
 #define QCOM_SCM_PAS_AUTH_AND_RESET_CMD	0x5
 #define QCOM_SCM_PAS_SHUTDOWN_CMD	0x6
 #define QCOM_SCM_PAS_IS_SUPPORTED_CMD	0x7
+#define QCOM_SCM_PAS_MSS_RESET		0xa
 extern bool __qcom_scm_pas_supported(struct device *dev, u32 peripheral);
 extern int  __qcom_scm_pas_init_image(struct device *dev, u32 peripheral,
 		dma_addr_t metadata_phys);
@@ -53,6 +54,7 @@ extern int  __qcom_scm_pas_mem_setup(struct device *dev, u32 peripheral,
 		phys_addr_t addr, phys_addr_t size);
 extern int  __qcom_scm_pas_auth_and_reset(struct device *dev, u32 peripheral);
 extern int  __qcom_scm_pas_shutdown(struct device *dev, u32 peripheral);
+extern int  __qcom_scm_pas_mss_reset(struct device *dev, bool reset);
 
 /* common error codes */
 #define QCOM_SCM_V2_EBUSY	-12