SM501: Check SM501 ID register on initialisation

When binding the driver, check the ID register for a valid identity, in case
the SM501 is not functioning correctly.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/mfd/sm501.c b/drivers/mfd/sm501.c
index e14d70e074189624c86f5c2bce2f9a596cad19ae..8135e4c3bf47b7cff7f61d2ae9e236fcefd0baeb 100644 (file)
--- a/drivers/mfd/sm501.c
+++ b/drivers/mfd/sm501.c
@@ -893,6 +893,7 @@ static int sm501_init_dev(struct sm501_devdata *sm)
 {
        resource_size_t mem_avail;
        unsigned long dramctrl;
+       unsigned long devid;
        int ret;
 
        mutex_init(&sm->clock_lock);
@@ -900,13 +901,18 @@ static int sm501_init_dev(struct sm501_devdata *sm)
 
        INIT_LIST_HEAD(&sm->devices);
 
-       dramctrl = readl(sm->regs + SM501_DRAM_CONTROL);
+       devid = readl(sm->regs + SM501_DEVICEID);
 
+       if ((devid & SM501_DEVICEID_IDMASK) != SM501_DEVICEID_SM501) {
+               dev_err(sm->dev, "incorrect device id %08lx\n", devid);
+               return -EINVAL;
+       }
+
+       dramctrl = readl(sm->regs + SM501_DRAM_CONTROL);
        mem_avail = sm501_mem_local[(dramctrl >> 13) & 0x7];
 
-       dev_info(sm->dev, "SM501 At %p: Version %08x, %ld Mb, IRQ %d\n",
-                sm->regs, readl(sm->regs + SM501_DEVICEID),
-                (unsigned long)mem_avail >> 20, sm->irq);
+       dev_info(sm->dev, "SM501 At %p: Version %08lx, %ld Mb, IRQ %d\n",
+                sm->regs, devid, (unsigned long)mem_avail >> 20, sm->irq);
 
        sm501_dump_gate(sm);
 

diff --git a/include/linux/sm501-regs.h b/include/linux/sm501-regs.h
index 8b4ecf02f9dcb4c3ef2a5e6c766d4e8fc1e63a43..014e73b31fc0ce92005f39c3bb00542c371729d8 100644 (file)
--- a/include/linux/sm501-regs.h
+++ b/include/linux/sm501-regs.h
@@ -109,6 +109,9 @@
 #define SM501_DEVICEID                 (0x000060)
 /* 0x050100A0 */
 
+#define SM501_DEVICEID_SM501           (0x05010000)
+#define SM501_DEVICEID_IDMASK          (0xffff0000)
+
 #define SM501_PLLCLOCK_COUNT           (0x000064)
 #define SM501_MISC_TIMING              (0x000068)
 #define SM501_CURRENT_SDRAM_CLOCK      (0x00006C)