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| author |  Serge Semin <fancer.lancer@gmail.com>
| 2024-04-24 18:06:43 +0300 |
|---|---|---|
| committer |  Mark Brown <broonie@kernel.org>
| 2024-05-03 11:09:23 +0900 |
| commit | e164be7e1e9373bd10e6b79924b0a6374752775e (patch) | |
| tree | 3ae85ce8759d335b598ac1bb4d25d81bccba2eb6 /drivers/spi | |
| parent | spi: dw: Convert to using BITS_TO_BYTES() macro (diff) | |
| download | linux-e164be7e1e9373bd10e6b79924b0a6374752775e.tar.gz linux-e164be7e1e9373bd10e6b79924b0a6374752775e.tar.bz2 linux-e164be7e1e9373bd10e6b79924b0a6374752775e.zip | |
spi: dw: Add a number of native CS auto-detection
Aside with the FIFO depth and DFS field size it's possible to auto-detect
a number of native chip-select synthesized in the DW APB/AHB SSI IP-core.
It can be done just by writing ones to the SER register. The number of
writable flags in the register is limited by the SSI_NUM_SLAVES IP-core
synthesize parameter. All the upper flags are read-only and wired to zero.
Based on that let's add the number of native CS auto-detection procedure
so the low-level platform drivers wouldn't need to manually set it up
unless it's required to set a constraint due to platform-specific reasons
(for instance, due to a hardware bug).
Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://lore.kernel.org/r/20240424150657.9678-3-fancer.lancer@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi-dw-core.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c index 722b5eb1f709..ddfdb903047a 100644 --- a/drivers/spi/spi-dw-core.c +++ b/drivers/spi/spi-dw-core.c @@ -835,6 +835,20 @@ static void dw_spi_hw_init(struct device *dev, struct dw_spi *dws) } /* + * Try to detect the number of native chip-selects if the platform + * driver didn't set it up. There can be up to 16 lines configured. + */ + if (!dws->num_cs) { + u32 ser; + + dw_writel(dws, DW_SPI_SER, 0xffff); + ser = dw_readl(dws, DW_SPI_SER); + dw_writel(dws, DW_SPI_SER, 0); + + dws->num_cs = hweight16(ser); + } + + /* * Try to detect the FIFO depth if not set by interface driver, * the depth could be from 2 to 256 from HW spec */ |