[Patch v6 03/10] firmware: qcom: scm: Use atomic SCM for cold boot

Andy Gross
2016-06-03T23:25:23Z

This patch changes the cold_set_boot_addr function to use atomic SCM
calls. cold_set_boot_addr required adding qcom_scm_call_atomic2 to
support the two arguments going to the smc call. Using atomic removes
the need for memory allocation and instead places all arguments in
registers.

Signed-off-by: Andy Gross <andy.gross@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
drivers/firmware/qcom_scm-32.c | 63 ++++++++++++++++++++++++++++++------------
1 file changed, 45 insertions(+), 18 deletions(-)

diff --git a/drivers/firmware/qcom_scm-32.c b/drivers/firmware/qcom_scm-32.c
index 0883292..5be6a12 100644
--- a/drivers/firmware/qcom_scm-32.c
+++ b/drivers/firmware/qcom_scm-32.c
@@ -342,6 +342,41 @@ static s32 qcom_scm_call_atomic1(u32 svc, u32 cmd, u32 arg1)
return r0;
}

+/**
+ * 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;
+
+ register u32 r0 asm("r0") = SCM_ATOMIC(svc, cmd, 2);
+ register u32 r1 asm("r1") = (u32)&context_id;
+ register u32 r2 asm("r2") = arg1;
+ register u32 r3 asm("r3") = arg2;
+
+ asm volatile(
+ __asmeq("%0", "r0")
+ __asmeq("%1", "r0")
+ __asmeq("%2", "r1")
+ __asmeq("%3", "r2")
+ __asmeq("%4", "r3")
+#ifdef REQUIRES_SEC
+ ".arch_extension sec\n"
+#endif
+ "smc #0 @ switch to secure world\n"
+ : "=r" (r0)
+ : "r" (r0), "r" (r1), "r" (r2), "r" (r3)
+ );
+ return r0;
+}
+
u32 qcom_scm_get_version(void)
{
int context_id;
@@ -378,22 +413,6 @@ u32 qcom_scm_get_version(void)
}
EXPORT_SYMBOL(qcom_scm_get_version);

-/*
- * Set the cold/warm boot address for one of the CPU cores.
- */
-static int qcom_scm_set_boot_addr(u32 addr, int flags)
-{
- struct {
- __le32 flags;
- __le32 addr;
- } cmd;
-
- cmd.addr = cpu_to_le32(addr);
- cmd.flags = cpu_to_le32(flags);
- return qcom_scm_call(QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_ADDR,
- &cmd, sizeof(cmd), NULL, 0);
-}
-
/**
* qcom_scm_set_cold_boot_addr() - Set the cold boot address for cpus
* @entry: Entry point function for the cpus
@@ -423,7 +442,8 @@ int __qcom_scm_set_cold_boot_addr(void *entry, const cpumask_t *cpus)
set_cpu_present(cpu, false);
}

- return qcom_scm_set_boot_addr(virt_to_phys(entry), flags);
+ return qcom_scm_call_atomic2(QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_ADDR,
+ flags, virt_to_phys(entry));
}

/**
@@ -439,6 +459,10 @@ int __qcom_scm_set_warm_boot_addr(void *entry, const cpumask_t *cpus)
int ret;
int flags = 0;
int cpu;
+ struct {
+ __le32 flags;
+ __le32 addr;
+ } cmd;

/*
* Reassign only if we are switching from hotplug entry point
@@ -454,7 +478,10 @@ int __qcom_scm_set_warm_boot_addr(void *entry, const cpumask_t *cpus)
if (!flags)
return 0;

- ret = qcom_scm_set_boot_addr(virt_to_phys(entry), flags);
+ cmd.addr = cpu_to_le32(virt_to_phys(entry));
+ cmd.flags = cpu_to_le32(flags);
+ ret = qcom_scm_call(QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_ADDR,
+ &cmd, sizeof(cmd), NULL, 0);
if (!ret) {
for_each_cpu(cpu, cpus)
qcom_scm_wb[cpu].entry = entry;
--
1.9.1