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authorAhmad Fatoum <ahmad@a3f.at>2019-11-15 08:52:56 +0100
committerSascha Hauer <s.hauer@pengutronix.de>2019-11-19 11:57:25 +0100
commit301893f3a91335e0fa569909cded5b56900ae1cb (patch)
tree8c4e075aaf5e02271901653a814f9b93605bfb96 /commands
parentc227eac51a8a0132ffcc9851072eb165e1eb7e14 (diff)
downloadbarebox-301893f3a91335e0fa569909cded5b56900ae1cb.tar.gz
commands: smc: verify PSCI_POWER_ON with interprocessor handshake
The use of psci_printf here, at least for the phytec-phycore-imx7, is racy, because access to the UART is not synchronized. This may lead to characters being swallowed and most certainly to garbled text. One way around this would be using separate UART ports for each core or even more generically, just dropping psci_printf and resorting to inter-core communication over shared-memory to check whether code execution succeeded. Signed-off-by: Ahmad Fatoum <ahmad@a3f.at> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'commands')
-rw-r--r--commands/smc.c61
1 files changed, 55 insertions, 6 deletions
diff --git a/commands/smc.c b/commands/smc.c
index eb96e58..9971036 100644
--- a/commands/smc.c
+++ b/commands/smc.c
@@ -3,23 +3,47 @@
#include <common.h>
#include <command.h>
#include <getopt.h>
+#include <dma.h>
+#include <linux/iopoll.h>
+#include <asm/barebox-arm-head.h>
#include <asm/psci.h>
#include <asm/secure.h>
#include <linux/arm-smccc.h>
-static void second_entry(void)
+#define STACK_SIZE 100
+#define HANDSHAKE_MAGIC 0xBA12EB0C
+#define ERROR_MAGIC 0xDEADBEEF
+
+struct cpu_context {
+ unsigned long stack[STACK_SIZE];
+ long handshake;
+};
+
+static void noinline cpu_handshake(long *handshake)
{
struct arm_smccc_res res;
- psci_printf("2nd CPU online, now turn off again\n");
+ writel(HANDSHAKE_MAGIC, handshake);
arm_smccc_smc(ARM_PSCI_0_2_FN_CPU_OFF,
0, 0, 0, 0, 0, 0, 0, &res);
- psci_printf("2nd CPU still alive?\n");
+ writel(ERROR_MAGIC, handshake);
+
+ while (1)
+ ;
+}
+
+static void __naked second_entry(unsigned long arg0)
+{
+ struct cpu_context *context = (void*)arg0;
+
+ arm_cpu_lowlevel_init();
+ arm_setup_stack((unsigned long)&context->stack[STACK_SIZE]);
+ barrier();
- while (1);
+ cpu_handshake(&context->handshake);
}
static const char *psci_xlate_str(long err)
@@ -54,6 +78,8 @@ static const char *psci_xlate_str(long err)
return errno_string;
}
+static struct cpu_context *context;
+
static int do_smc(int argc, char *argv[])
{
long ret;
@@ -79,12 +105,35 @@ static int do_smc(int argc, char *argv[])
printf("found psci version %ld.%ld\n", res.a0 >> 16, res.a0 & 0xffff);
break;
case 'c':
+ if (!context)
+ context = dma_alloc_coherent(sizeof(*context),
+ DMA_ADDRESS_BROKEN);
+
+ if (!context) {
+ printf("Out of memory\n");
+ return COMMAND_ERROR;
+ }
+
arm_smccc_smc(ARM_PSCI_0_2_FN_CPU_ON,
- 1, (unsigned long)second_entry, 0, 0, 0, 0, 0, &res);
+ 1, (unsigned long)second_entry, (unsigned long)context,
+ 0, 0, 0, 0, &res);
ret = (long)res.a0;
printf("CPU_ON returns with: %s\n", psci_xlate_str(ret));
- if (ret)
+ if (ret) {
+ unsigned long magic = readl(&context->handshake);
+ if (magic == ERROR_MAGIC)
+ printf("Turning off CPU had failed\n");
return COMMAND_ERROR;
+ }
+
+ readl_poll_timeout(&context->handshake, ret,
+ ret != HANDSHAKE_MAGIC, USEC_PER_SEC);
+ if (ret == 0) {
+ printf("Second CPU handshake timed out.\n");
+ return COMMAND_ERROR;
+ }
+
+ printf("Second CPU handshake successful.\n");
}
}