[PATCH 1/3] mtd: m25p80: fix module autoloading for "jedec,spi-nor" and "spi-nor"

From: Brian Norris
Date: Mon Nov 16 2015 - 17:35:23 EST

Commit 43163022927b ("mtd: m25p80: allow arbitrary OF matching for
"jedec,spi-nor"") moved the "jedec,spi-nor" handling from the
spi_device_id table to the of_match_table, to better handle matching
complex device tree compatible strings. With that patch, device tree
support works as expected when m25p80.c is built into the kernel.

However, that commit ignored the fact that:

(1) (non-DT) platform devices might want to use the "spi-nor" string
for matching with this driver, rather than picking an arbitrary one
like "m25p80"
(2) the core SPI uevent/modalias code doesn't yet support kernel module
autoloading via of_match_table strings; so for DT-based devices, it
will only report (part of) the first compatible string used

Problem (1) has been reported previously, and I forgot to patch it up

Problem (2) was noticed recently here:

Specifically, this patch fixes m25p80.ko module autoloading for cases
like this:

flash@xxx {
compatible = "jedec,spi-nor";

because modalias of "spi:spi-nor" (the only module loading info provided
by the SPI core for this device) will now be listed as an alias in

Notably, it does *not* help cases like this:

flash@xxx {
compatible = "vendor,shiny-new-device", "jedec,spi-nor";

unless we also list "shiny-new-device" in m25p_ids[]. There has been
discussion on future work for this issue here:

Cc: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
Tested module autoload with each of the following:

compatible = "m25p80";
compatible = "jedec,spi-nor";

drivers/mtd/devices/m25p80.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index f002a8f75374..151b453d0867 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -179,7 +179,7 @@ static int m25p_probe(struct spi_device *spi)
struct m25p *flash;
struct spi_nor *nor;
enum read_mode mode = SPI_NOR_NORMAL;
- char *flash_name = NULL;
+ char *flash_name;
int ret;

data = dev_get_platdata(&spi->dev);
@@ -219,6 +219,8 @@ static int m25p_probe(struct spi_device *spi)
if (data && data->type)
flash_name = data->type;
+ else if (!strcmp(spi->modalias, "spi-nor"))
+ flash_name = NULL; /* auto-detect */
flash_name = spi->modalias;

@@ -253,6 +255,13 @@ static int m25p_remove(struct spi_device *spi)
static const struct spi_device_id m25p_ids[] = {
+ * Allow non-DT platform devices to bind to the "spi-nor" modalias, and
+ * hack around the fact that the SPI core does not provide uevent
+ * matching for .of_match_table
+ */
+ {"spi-nor"},
+ /*
* Entries not used in DTs that should be safe to drop after replacing
* them with "nor-jedec" in platform data.

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