[PATCH] powerpc/scom: Change scom_read() and scom_write() to return errors
Benjamin Herrenschmidt
benh at kernel.crashing.org
Thu Aug 29 16:55:45 EST 2013
scom_read() now returns the read value via a pointer argument and
both functions return an int error code
Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
---
arch/powerpc/include/asm/scom.h | 23 +++++++++++++++++------
arch/powerpc/platforms/wsp/scom_smp.c | 18 +++++++++++++-----
arch/powerpc/platforms/wsp/scom_wsp.c | 12 ++++++++----
arch/powerpc/platforms/wsp/wsp.c | 13 +++++++------
arch/powerpc/sysdev/scom.c | 3 +--
5 files changed, 46 insertions(+), 23 deletions(-)
diff --git a/arch/powerpc/include/asm/scom.h b/arch/powerpc/include/asm/scom.h
index 0cabfd7..07dcdcf 100644
--- a/arch/powerpc/include/asm/scom.h
+++ b/arch/powerpc/include/asm/scom.h
@@ -54,8 +54,8 @@ struct scom_controller {
scom_map_t (*map)(struct device_node *ctrl_dev, u64 reg, u64 count);
void (*unmap)(scom_map_t map);
- u64 (*read)(scom_map_t map, u32 reg);
- void (*write)(scom_map_t map, u32 reg, u64 value);
+ int (*read)(scom_map_t map, u32 reg, u64 *value);
+ int (*write)(scom_map_t map, u32 reg, u64 value);
};
extern const struct scom_controller *scom_controller;
@@ -133,10 +133,18 @@ static inline void scom_unmap(scom_map_t map)
* scom_read - Read a SCOM register
* @map: Result of scom_map
* @reg: Register index within that map
+ * @value: Updated with the value read
+ *
+ * Returns 0 (success) or a negative error code
*/
-static inline u64 scom_read(scom_map_t map, u32 reg)
+static inline int scom_read(scom_map_t map, u32 reg, u64 *value)
{
- return scom_controller->read(map, reg);
+ int rc;
+
+ rc = scom_controller->read(map, reg, value);
+ if (rc)
+ *value = 0xfffffffffffffffful;
+ return rc;
}
/**
@@ -144,12 +152,15 @@ static inline u64 scom_read(scom_map_t map, u32 reg)
* @map: Result of scom_map
* @reg: Register index within that map
* @value: Value to write
+ *
+ * Returns 0 (success) or a negative error code
*/
-static inline void scom_write(scom_map_t map, u32 reg, u64 value)
+static inline int scom_write(scom_map_t map, u32 reg, u64 value)
{
- scom_controller->write(map, reg, value);
+ return scom_controller->write(map, reg, value);
}
+
#endif /* CONFIG_PPC_SCOM */
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
diff --git a/arch/powerpc/platforms/wsp/scom_smp.c b/arch/powerpc/platforms/wsp/scom_smp.c
index b56b70a..268bc89 100644
--- a/arch/powerpc/platforms/wsp/scom_smp.c
+++ b/arch/powerpc/platforms/wsp/scom_smp.c
@@ -116,7 +116,14 @@ static int a2_scom_ram(scom_map_t scom, int thread, u32 insn, int extmask)
scom_write(scom, SCOM_RAMIC, cmd);
- while (!((val = scom_read(scom, SCOM_RAMC)) & mask)) {
+ for (;;) {
+ if (scom_read(scom, SCOM_RAMC, &val) != 0) {
+ pr_err("SCOM error on instruction 0x%08x, thread %d\n",
+ insn, thread);
+ return -1;
+ }
+ if (val & mask)
+ break;
pr_devel("Waiting on RAMC = 0x%llx\n", val);
if (++n == 3) {
pr_err("RAMC timeout on instruction 0x%08x, thread %d\n",
@@ -151,9 +158,7 @@ static int a2_scom_getgpr(scom_map_t scom, int thread, int gpr, int alt,
if (rc)
return rc;
- *out_gpr = scom_read(scom, SCOM_RAMD);
-
- return 0;
+ return scom_read(scom, SCOM_RAMD, out_gpr);
}
static int a2_scom_getspr(scom_map_t scom, int thread, int spr, u64 *out_spr)
@@ -353,7 +358,10 @@ int a2_scom_startup_cpu(unsigned int lcpu, int thr_idx, struct device_node *np)
pr_devel("Bringing up CPU%d using SCOM...\n", lcpu);
- pccr0 = scom_read(scom, SCOM_PCCR0);
+ if (scom_read(scom, SCOM_PCCR0, &pccr0) != 0) {
+ printk(KERN_ERR "XSCOM failure readng PCCR0 on CPU%d\n", lcpu);
+ return -1;
+ }
scom_write(scom, SCOM_PCCR0, pccr0 | SCOM_PCCR0_ENABLE_DEBUG |
SCOM_PCCR0_ENABLE_RAM);
diff --git a/arch/powerpc/platforms/wsp/scom_wsp.c b/arch/powerpc/platforms/wsp/scom_wsp.c
index 4052e22..54172c4 100644
--- a/arch/powerpc/platforms/wsp/scom_wsp.c
+++ b/arch/powerpc/platforms/wsp/scom_wsp.c
@@ -50,18 +50,22 @@ static void wsp_scom_unmap(scom_map_t map)
iounmap((void *)map);
}
-static u64 wsp_scom_read(scom_map_t map, u32 reg)
+static int wsp_scom_read(scom_map_t map, u32 reg, u64 *value)
{
u64 __iomem *addr = (u64 __iomem *)map;
- return in_be64(addr + reg);
+ *value = in_be64(addr + reg);
+
+ return 0;
}
-static void wsp_scom_write(scom_map_t map, u32 reg, u64 value)
+static int wsp_scom_write(scom_map_t map, u32 reg, u64 value)
{
u64 __iomem *addr = (u64 __iomem *)map;
- return out_be64(addr + reg, value);
+ out_be64(addr + reg, value);
+
+ return 0;
}
static const struct scom_controller wsp_scom_controller = {
diff --git a/arch/powerpc/platforms/wsp/wsp.c b/arch/powerpc/platforms/wsp/wsp.c
index d25cc96..ddb6efe 100644
--- a/arch/powerpc/platforms/wsp/wsp.c
+++ b/arch/powerpc/platforms/wsp/wsp.c
@@ -89,6 +89,7 @@ void wsp_halt(void)
struct device_node *dn;
struct device_node *mine;
struct device_node *me;
+ int rc;
me = of_get_cpu_node(smp_processor_id(), NULL);
mine = scom_find_parent(me);
@@ -101,15 +102,15 @@ void wsp_halt(void)
/* read-modify-write it so the HW probe does not get
* confused */
- val = scom_read(m, 0);
- val |= 1;
- scom_write(m, 0, val);
+ rc = scom_read(m, 0, &val);
+ if (rc == 0)
+ scom_write(m, 0, val | 1);
scom_unmap(m);
}
m = scom_map(mine, 0, 1);
- val = scom_read(m, 0);
- val |= 1;
- scom_write(m, 0, val);
+ rc = scom_read(m, 0, &val);
+ if (rc == 0)
+ scom_write(m, 0, val | 1);
/* should never return */
scom_unmap(m);
}
diff --git a/arch/powerpc/sysdev/scom.c b/arch/powerpc/sysdev/scom.c
index 9193e12..10f1d9e 100644
--- a/arch/powerpc/sysdev/scom.c
+++ b/arch/powerpc/sysdev/scom.c
@@ -137,8 +137,7 @@ static int scom_val_get(void *data, u64 *val)
if (!scom_map_ok(ent->map))
return -EFAULT;
- *val = scom_read(ent->map, 0);
- return 0;
+ return scom_read(ent->map, 0, val);
}
DEFINE_SIMPLE_ATTRIBUTE(scom_val_fops, scom_val_get, scom_val_set,
"0x%llx\n");
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