firmware: arm_scmi: Add qcom smc/hvc transport support

This change adds the support for SCMI message exchange on Qualcomm
virtual platforms.

The hypervisor associates an object-id also known as capability-id
with each smc/hvc doorbell object. The capability-id is used to
identify the doorbell from the VM's capability namespace, similar
to a file-descriptor.

The hypervisor, in addition to the function-id, expects the capability-id
to be passed in x1 register when SMC/HVC call is invoked.

The capability-id is allocated by the hypervisor on bootup and is stored in
the shmem region by the firmware before starting Linux.

Signed-off-by: Nikunj Kela <quic_nkela@quicinc.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
Link: https://lore.kernel.org/r/20231009191437.27926-3-quic_nkela@quicinc.com
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 87383c05424bdfd05cfa035f77ab24257f9451e4..09371f40d61f48a72abc850c772ac5ec277ec114 100644 (file)
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -2915,6 +2915,7 @@ static const struct of_device_id scmi_of_match[] = {
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC
        { .compatible = "arm,scmi-smc", .data = &scmi_smc_desc},
        { .compatible = "arm,scmi-smc-param", .data = &scmi_smc_desc},
+       { .compatible = "qcom,scmi-smc", .data = &scmi_smc_desc},
 #endif
 #ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO
        { .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc},

diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
index 8eba60a419754a08b8f99914f4369c04c70d7fe2..7611e9665038dc0eeb0d49a36ac84bc52fa03396 100644 (file)
--- a/drivers/firmware/arm_scmi/smc.c
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -15,6 +15,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
+#include <linux/limits.h>
 #include <linux/processor.h>
 #include <linux/slab.h>
 
@@ -50,6 +51,8 @@
  * @func_id: smc/hvc call function id
  * @param_page: 4K page number of the shmem channel
  * @param_offset: Offset within the 4K page of the shmem channel
+ * @cap_id: smc/hvc doorbell's capability id to be used on Qualcomm virtual
+ *         platforms
  */
 
 struct scmi_smc {
@@ -63,6 +66,7 @@ struct scmi_smc {
        unsigned long func_id;
        unsigned long param_page;
        unsigned long param_offset;
+       unsigned long cap_id;
 };
 
 static irqreturn_t smc_msg_done_isr(int irq, void *data)
@@ -124,6 +128,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
                          bool tx)
 {
        struct device *cdev = cinfo->dev;
+       unsigned long cap_id = ULONG_MAX;
        struct scmi_smc *scmi_info;
        resource_size_t size;
        struct resource res;
@@ -162,6 +167,18 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
        if (ret < 0)
                return ret;
 
+       if (of_device_is_compatible(dev->of_node, "qcom,scmi-smc")) {
+               void __iomem *ptr = (void __iomem *)scmi_info->shmem + size - 8;
+               /* The capability-id is kept in last 8 bytes of shmem.
+                *     +-------+ <-- 0
+                *     | shmem |
+                *     +-------+ <-- size - 8
+                *     | capId |
+                *     +-------+ <-- size
+                */
+               memcpy_fromio(&cap_id, ptr, sizeof(cap_id));
+       }
+
        if (of_device_is_compatible(dev->of_node, "arm,scmi-smc-param")) {
                scmi_info->param_page = SHMEM_PAGE(res.start);
                scmi_info->param_offset = SHMEM_OFFSET(res.start);
@@ -184,6 +201,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
        }
 
        scmi_info->func_id = func_id;
+       scmi_info->cap_id = cap_id;
        scmi_info->cinfo = cinfo;
        smc_channel_lock_init(scmi_info);
        cinfo->transport_info = scmi_info;
@@ -220,8 +238,13 @@ 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, scmi_info->param_page,
-                            scmi_info->param_offset, 0, 0, 0, 0, 0, &res);
+       if (scmi_info->cap_id != ULONG_MAX)
+               arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->cap_id, 0,
+                                    0, 0, 0, 0, 0, &res);
+       else
+               arm_smccc_1_1_invoke(scmi_info->func_id, scmi_info->param_page,
+                                    scmi_info->param_offset, 0, 0, 0, 0, 0,
+                                    &res);
 
        /* Only SMCCC_RET_NOT_SUPPORTED is valid error code */
        if (res.a0) {