Re: [PATCH v4 4/4] firmware: arm_scmi: Add qcom hvc/shmem transport support
From: Brian Masney <bmasney@redhat.com>
Date: 2023-10-02 18:35:10
Also in:
linux-arm-kernel, linux-arm-msm, lkml
On Mon, Sep 11, 2023 at 12:43:59PM -0700, Nikunj Kela wrote:
quoted hunk ↗ jump to hunk
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 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 HVC call is invoked. The function-id & capability-id are allocated by the hypervisor on bootup and are stored in the shmem region by the firmware before starting Linux. Signed-off-by: Nikunj Kela <redacted> --- drivers/firmware/arm_scmi/driver.c | 1 + drivers/firmware/arm_scmi/smc.c | 47 ++++++++++++++++++++++++++---- 2 files changed, 43 insertions(+), 5 deletions(-)diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index 87383c05424b..ea344bc6ae49 100644 --- 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-hvc-shmem", .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 0a0b7e401159..94ec07fdc14a 100644 --- a/drivers/firmware/arm_scmi/smc.c +++ b/drivers/firmware/arm_scmi/smc.c@@ -50,6 +50,9 @@ * @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: hvc doorbell's capability id to be used on Qualcomm virtual + * platforms + * @qcom_xport: Flag to indicate the transport on Qualcomm virtual platforms */ struct scmi_smc {@@ -63,6 +66,8 @@ struct scmi_smc { u32 func_id; u32 param_page; u32 param_offset; + u64 cap_id; + bool qcom_xport; };
[snip]
quoted hunk ↗ jump to hunk
static irqreturn_t smc_msg_done_isr(int irq, void *data)@@ -129,6 +134,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, struct resource res; struct device_node *np; u32 func_id; + u64 cap_id; int ret;
[snip]
+ func_id = readl((void __iomem *)(scmi_info->shmem) + size - 16); +#ifdef CONFIG_ARM64 + cap_id = readq((void __iomem *)(scmi_info->shmem) + size - 8); +#else + /* capability-id is 32 bit wide on 32bit machines */ + cap_id = readl((void __iomem *)(scmi_info->shmem) + size - 8); +#endif
The 32 bit case is defined as a u64 in two places above.
+ + /* The func-id & capability-id are kept in last 16 bytes of shmem. + * +-------+ + * | | + * | shmem | + * | | + * | | + * +-------+ <-- (size - 16) + * | funcId| + * +-------+ <-- (size - 8) + * | capId | + * +-------+ <-- size + */
Personally I'd add one more space to the right side of the table after funcId.
- arm_smccc_1_1_invoke(scmi_info->func_id, page, offset, 0, 0, 0, 0, 0, - &res); + if (scmi_info->qcom_xport) + arm_smccc_1_1_hvc(scmi_info->func_id, cap_id, 0, 0, 0, 0, 0, 0, + &res); + else + arm_smccc_1_1_invoke(scmi_info->func_id, page, offset, 0, 0, 0, + 0, 0, &res);
Does it make sense to call this variable qcom_xport? Would hvc_xport be a more appropriate name? Brian