[PATCH v2 2/2] firmware: arm_scmi: Augment SMC/HVC to allow optional parameters

From: Nikunj Kela
Date: Mon Apr 10 2023 - 14:21:49 EST


This patch add support for passing parameters to smc/hvc calls.
This patch is useful when multiple scmi instances are using same
smc-id and firmware needs to distiguish among the instances.

Signed-off-by: Nikunj Kela <quic_nkela@xxxxxxxxxxx>
---
drivers/firmware/arm_scmi/smc.c | 72 ++++++++++++++++++++++++++++++++-
1 file changed, 71 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
index 93272e4bbd12..c57d2f3fab87 100644
--- a/drivers/firmware/arm_scmi/smc.c
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -20,6 +20,16 @@

#include "common.h"

+#define MAX_PARAM_COUNT 6
+
+/**
+ * scmi_smc_param_t - parameter type for SCMI smc/hvc call
+ */
+typedef union {
+ u64 x;
+ u32 w;
+} scmi_smc_param_t;
+
/**
* struct scmi_smc - Structure representing a SCMI smc transport
*
@@ -30,6 +40,8 @@
* @inflight: Atomic flag to protect access to Tx/Rx shared memory area.
* Used when operating in atomic mode.
* @func_id: smc/hvc call function id
+ * @is_smc64: A flag, indicating smc64 calling convention.
+ * @params: Optional, smc/hvc call parameters.
*/

struct scmi_smc {
@@ -40,8 +52,55 @@ struct scmi_smc {
#define INFLIGHT_NONE MSG_TOKEN_MAX
atomic_t inflight;
u32 func_id;
+ bool is_smc64;
+ scmi_smc_param_t params[MAX_PARAM_COUNT];
};

+static void populate_smc_params(struct device *dev, struct scmi_smc *scmi_info)
+{
+ struct device_node *np = dev->of_node;
+ u64 params64[MAX_PARAM_COUNT] = { 0 };
+ u32 params32[MAX_PARAM_COUNT] = { 0 };
+ int i, count;
+
+#ifdef CONFIG_ARM64
+ if (scmi_info->is_smc64) {
+ count = of_property_read_variable_u64_array(np,
+ "arm,smc64-params",
+ &params64[0], 1,
+ MAX_PARAM_COUNT);
+ if (count == -EINVAL) /* if property is not defined */
+ return;
+
+ if (count > 0) /* populate the parameters */
+ for (i = 0; i < count; i++)
+ scmi_info->params[i].x = params64[i];
+ else
+ goto param_err;
+ } else {
+#else
+ {
+#endif
+ count = of_property_read_variable_u32_array(np,
+ "arm,smc32-params",
+ &params32[0], 1,
+ MAX_PARAM_COUNT);
+ if (count == -EINVAL) /* if property is not defined */
+ return;
+
+ if (count > 0) /* populate the parameters */
+ for (i = 0; i < count; i++)
+ scmi_info->params[i].w = params32[i];
+ else
+ goto param_err;
+ }
+
+ return;
+
+param_err:
+ dev_warn(dev, "failed to read smc/hvc call parameters\n");
+}
+
static irqreturn_t smc_msg_done_isr(int irq, void *data)
{
struct scmi_smc *scmi_info = data;
@@ -156,6 +215,8 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
}

scmi_info->func_id = func_id;
+ scmi_info->is_smc64 = ARM_SMCCC_IS_64(func_id);
+ populate_smc_params(dev, scmi_info);
scmi_info->cinfo = cinfo;
smc_channel_lock_init(scmi_info);
cinfo->transport_info = scmi_info;
@@ -179,6 +240,7 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
{
struct scmi_smc *scmi_info = cinfo->transport_info;
struct arm_smccc_res res;
+ scmi_smc_param_t *p = scmi_info->params;

/*
* Channel will be released only once response has been
@@ -188,7 +250,15 @@ static int smc_send_message(struct scmi_chan_info *cinfo,

shmem_tx_prepare(scmi_info->shmem, xfer, cinfo);

- arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+#ifdef CONFIG_ARM64
+ if (scmi_info->is_smc64)
+ arm_smccc_1_1_invoke(scmi_info->func_id, p[0].x, p[1].x, p[2].x,
+ p[3].x, p[4].x, p[5].x, 0, &res);
+ else
+#endif
+ arm_smccc_1_1_invoke(scmi_info->func_id, p[0].w, p[1].w, p[2].w,
+ p[3].w, p[4].w, p[5].w, 0, &res);
+

/* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
if (res.a0) {
--
2.17.1