firmware: qcom_scm-32: Create common legacy atomic call

Per [1], legacy calling convention supports up to 5 arguments and 3
return values. Create one function to support this combination, and
remove the original "atomic1" and "atomic2" variants for 1 and 2
arguments. This more closely aligns scm_legacy implementation with
scm_smc implementation.

[1]: https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/soc/qcom/scm.c?h=kernel.lnx.4.9.r28-rel#n1024

Tested-by: Brian Masney <masneyb@onstation.org> # arm32
Tested-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Elliot Berman <eberman@codeaurora.org>
Link: https://lore.kernel.org/r/1578431066-19600-14-git-send-email-eberman@codeaurora.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/firmware/qcom_scm-32.c

@@ -266,6 +266,8 @@ static int qcom_scm_call(struct device *dev, const struct qcom_scm_desc *desc,
 	return ret;
 }
 
+#define SCM_LEGACY_ATOMIC_N_REG_ARGS	5
+#define SCM_LEGACY_ATOMIC_FIRST_REG_IDX	2
 #define SCM_LEGACY_CLASS_REGISTER		(0x2 << 8)
 #define SCM_LEGACY_MASK_IRQS		BIT(5)
 #define SCM_LEGACY_ATOMIC_ID(svc, cmd, n) \
@@ -275,44 +277,35 @@ static int qcom_scm_call(struct device *dev, const struct qcom_scm_desc *desc,
 				(n & 0xf))
 
 /**
- * qcom_scm_call_atomic1() - Send an atomic SCM command with one argument
- * @svc_id: service identifier
- * @cmd_id: command identifier
- * @arg1: first argument
+ * qcom_scm_call_atomic() - Send an atomic SCM command with up to 5 arguments
+ * and 3 return values
+ * @desc: SCM call descriptor containing arguments
+ * @res:  SCM call return values
  *
  * This shall only be used with commands that are guaranteed to be
  * uninterruptable, atomic and SMP safe.
  */
-static s32 qcom_scm_call_atomic1(u32 svc, u32 cmd, u32 arg1)
+static int qcom_scm_call_atomic(const struct qcom_scm_desc *desc,
+				struct qcom_scm_res *res)
 {
 	int context_id;
-	struct arm_smccc_res res;
+	struct arm_smccc_res smc_res;
+	size_t arglen = desc->arginfo & 0xf;
 
-	arm_smccc_smc(SCM_LEGACY_ATOMIC_ID(svc, cmd, 1),
-		      (unsigned long)&context_id, arg1, 0, 0, 0, 0, 0, &res);
+	BUG_ON(arglen > SCM_LEGACY_ATOMIC_N_REG_ARGS);
 
-	return res.a0;
-}
+	arm_smccc_smc(SCM_LEGACY_ATOMIC_ID(desc->svc, desc->cmd, arglen),
+		      (unsigned long)&context_id,
+		      desc->args[0], desc->args[1], desc->args[2],
+		      desc->args[3], desc->args[4], 0, &smc_res);
 
-/**
- * qcom_scm_call_atomic2() - Send an atomic SCM command with two arguments
- * @svc_id:	service identifier
- * @cmd_id:	command identifier
- * @arg1:	first argument
- * @arg2:	second argument
- *
- * This shall only be used with commands that are guaranteed to be
- * uninterruptable, atomic and SMP safe.
- */
-static s32 qcom_scm_call_atomic2(u32 svc, u32 cmd, u32 arg1, u32 arg2)
-{
-	int context_id;
-	struct arm_smccc_res res;
-
-	arm_smccc_smc(SCM_LEGACY_ATOMIC_ID(svc, cmd, 2),
-		      (unsigned long)&context_id, arg1, 0, 0, 0, 0, 0, &res);
+	if (res) {
+		res->result[0] = smc_res.a1;
+		res->result[1] = smc_res.a2;
+		res->result[2] = smc_res.a3;
+	}
 
-	return res.a0;
+	return smc_res.a0;
 }
 
 /**
@@ -333,6 +326,10 @@ int __qcom_scm_set_cold_boot_addr(void *entry, const cpumask_t *cpus)
 		QCOM_SCM_FLAG_COLDBOOT_CPU2,
 		QCOM_SCM_FLAG_COLDBOOT_CPU3,
 	};
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_BOOT,
+		.cmd = QCOM_SCM_BOOT_SET_ADDR,
+	};
 
 	if (!cpus || (cpus && cpumask_empty(cpus)))
 		return -EINVAL;
@@ -344,8 +341,11 @@ int __qcom_scm_set_cold_boot_addr(void *entry, const cpumask_t *cpus)
 			set_cpu_present(cpu, false);
 	}
 
-	return qcom_scm_call_atomic2(QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_SET_ADDR,
-				    flags, virt_to_phys(entry));
+	desc.args[0] = flags;
+	desc.args[1] = virt_to_phys(entry);
+	desc.arginfo = QCOM_SCM_ARGS(2);
+
+	return qcom_scm_call_atomic(&desc, NULL);
 }
 
 /**
@@ -404,8 +404,14 @@ int __qcom_scm_set_warm_boot_addr(struct device *dev, void *entry,
  */
 void __qcom_scm_cpu_power_down(u32 flags)
 {
-	qcom_scm_call_atomic1(QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_TERMINATE_PC,
-			flags & QCOM_SCM_FLUSH_FLAG_MASK);
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_BOOT,
+		.cmd = QCOM_SCM_BOOT_TERMINATE_PC,
+		.args[0] = flags & QCOM_SCM_FLUSH_FLAG_MASK,
+		.arginfo = QCOM_SCM_ARGS(1),
+	};
+
+	qcom_scm_call_atomic(&desc, NULL);
 }
 
 int __qcom_scm_is_call_available(struct device *dev, u32 svc_id, u32 cmd_id)
@@ -601,8 +607,16 @@ int __qcom_scm_pas_mss_reset(struct device *dev, bool reset)
 
 int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
 {
-	return qcom_scm_call_atomic2(QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_SET_DLOAD_MODE,
-				     enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0, 0);
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_BOOT,
+		.cmd = QCOM_SCM_BOOT_SET_DLOAD_MODE,
+	};
+
+	desc.args[0] = QCOM_SCM_BOOT_SET_DLOAD_MODE;
+	desc.args[1] = enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0;
+	desc.arginfo = QCOM_SCM_ARGS(2);
+
+	return qcom_scm_call_atomic(&desc, NULL);
 }
 
 int __qcom_scm_set_remote_state(struct device *dev, u32 state, u32 id)
@@ -664,18 +678,34 @@ int __qcom_scm_io_readl(struct device *dev, phys_addr_t addr,
 			unsigned int *val)
 {
 	int ret;
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_IO,
+		.cmd = QCOM_SCM_IO_READ,
+	};
+	struct qcom_scm_res res;
+
+	desc.args[0] = addr;
+	desc.arginfo = QCOM_SCM_ARGS(1);
 
-	ret = qcom_scm_call_atomic1(QCOM_SCM_SVC_IO, QCOM_SCM_IO_READ, addr);
+	ret = qcom_scm_call_atomic(&desc, &res);
 	if (ret >= 0)
-		*val = ret;
+		*val = res.result[0];
 
 	return ret < 0 ? ret : 0;
 }
 
 int __qcom_scm_io_writel(struct device *dev, phys_addr_t addr, unsigned int val)
 {
-	return qcom_scm_call_atomic2(QCOM_SCM_SVC_IO, QCOM_SCM_IO_WRITE,
-				     addr, val);
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_IO,
+		.cmd = QCOM_SCM_IO_WRITE,
+	};
+
+	desc.args[0] = addr;
+	desc.args[1] = val;
+	desc.arginfo = QCOM_SCM_ARGS(2);
+
+	return qcom_scm_call_atomic(&desc, NULL);
 }
 
 int __qcom_scm_qsmmu500_wait_safe_toggle(struct device *dev, bool enable)