Add minimal runtime PM support (enable on probe, disable on remove), to
ensure proper operation with a parent device that uses runtime PM.
This is needed on systems where the FLASH is connected to a bus
controller that is contained in a PM domain and/or has a gateable
functional clock. In such cases, before accessing any device connected
to the external bus, the PM domain must be powered up, and/or the
functional clock must be enabled, which is typically handled through
runtime PM by the bus controller driver.
An example of this is the Renesas APE6-EVM development board, which has
an Ethernet controller and a CFI FLASH connected to the Bus State
Controller (BSC) of an R-Mobile APE6 SoC.
As long as the Ethernet driver, which had Runtime PM support since
commit 3a611e26e958b037 ("net/smsc911x: Add minimal runtime PM
support"), keeps the BSC powered, accessing the FLASH works.
When the ethernet node in r8a73a4-ape6evm.dts is disabled, the BSC is
never powered up, and the kernel crashes when trying to access the
FLASH:
Unhandled fault: imprecise external abort (0x1406) at 0x00000000
pgd = (ptrval)
[00000000] *pgd=7fef2835
Internal error: : 1406 [#1] SMP ARM
CPU: 0 PID: 122 Comm: hd Tainted: G W 5.5.0-rc1-ape6evm-00814-g38ca966db25b9dbd-dirty #136
Hardware name: Generic R8A73A4 (Flattened Device Tree)
PC is at chip_ready+0x12c/0x380
LR is at chip_ready+0x10c/0x380
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
Probably the device should be powered down after probing, and powered
up/down on-demand in the various {get,put}_chip() functions. However,
that is an optimization which touches more intimidate details of the
internal MTD API, and can be done later.
---
drivers/mtd/maps/physmap-core.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/maps/physmap-core.c b/drivers/mtd/maps/physmap-core.c
index a9f7964e2edb6668..8f7f966fa9a7ee8a 100644
--- a/drivers/mtd/maps/physmap-core.c
+++ b/drivers/mtd/maps/physmap-core.c
@@ -38,6 +38,7 @@
#include <linux/mtd/cfi_endian.h>
#include <linux/io.h>
#include <linux/of_device.h>
+#include <linux/pm_runtime.h>
#include <linux/gpio/consumer.h>
#include "physmap-gemini.h"
@@ -64,16 +65,16 @@ static int physmap_flash_remove(struct platform_device *dev)
{
struct physmap_flash_info *info;
struct physmap_flash_data *physmap_data;
- int i, err;
+ int i, err = 0;
info = platform_get_drvdata(dev);
if (!info)
- return 0;
+ goto out;
if (info->cmtd) {
err = mtd_device_unregister(info->cmtd);
if (err)
- return err;
+ goto out;
if (info->cmtd != info->mtds[0])
mtd_concat_destroy(info->cmtd);
@@ -88,7 +89,10 @@ static int physmap_flash_remove(struct platform_device *dev)
if (physmap_data && physmap_data->exit)
physmap_data->exit(dev);
- return 0;
+out:
+ pm_runtime_put(&dev->dev);
+ pm_runtime_disable(&dev->dev);
+ return err;
}
static void physmap_set_vpp(struct map_info *map, int state)
@@ -484,13 +488,19 @@ static int physmap_flash_probe(struct platform_device *dev)
return -EINVAL;
}
+ pm_runtime_enable(&dev->dev);
+ pm_runtime_get_sync(&dev->dev);
+
if (dev->dev.of_node)
err = physmap_flash_of_init(dev);
else
err = physmap_flash_pdata_init(dev);
- if (err)
+ if (err) {
+ pm_runtime_put(&dev->dev);
+ pm_runtime_disable(&dev->dev);
return err;
+ }
for (i = 0; i < info->nmaps; i++) {
struct resource *res;
--
2.17.1
