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spi: rzv2h-rspi: add support for loopback mode

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Add support for loopback mode for debugging purposes, allowing us to
test the SPI controller at the maximum SPI transfer clock without being
limited by external wiring.

Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
Link: https://patch.msgid.link/20251119161434.595677-10-cosmin-gabriel.tanislav.xa@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Cosmin Tanislav 2025-11-19 18:14:30 +02:00 committed by Mark Brown
parent 9c9bf4fdc5
commit bc4f0b1e39
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GPG Key ID: 24D68B725D5487D0
1 changed files with 10 additions and 1 deletions
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11
drivers/spi/spi-rzv2h-rspi.c
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@ -24,6 +24,7 @@
/* Registers */
#define RSPI_SPDR 0x00
#define RSPI_SPCR 0x08
#define RSPI_SPPCR 0x0e
#define RSPI_SSLP 0x10
#define RSPI_SPBR 0x11
#define RSPI_SPSCR 0x13
@ -40,6 +41,9 @@
#define RSPI_SPCR_SCKASE BIT(12)
#define RSPI_SPCR_SPE BIT(0)
/* Register SPPCR */
#define RSPI_SPPCR_SPLP2 BIT(1)
/* Register SPBR */
#define RSPI_SPBR_SPR_MIN 0
#define RSPI_SPBR_SPR_PCLK_MIN 1
@ -345,6 +349,7 @@ static int rzv2h_rspi_prepare_message(struct spi_controller *ctlr,
u8 bits_per_word;
u32 conf32;
u16 conf16;
u8 conf8;
/* Make sure SPCR.SPE is 0 before amending the configuration */
rzv2h_rspi_spe_disable(rspi);
@ -389,6 +394,10 @@ static int rzv2h_rspi_prepare_message(struct spi_controller *ctlr,
/* Use SPCMD0 only */
writeb(0x0, rspi->base + RSPI_SPSCR);
/* Setup loopback */
conf8 = FIELD_PREP(RSPI_SPPCR_SPLP2, !!(spi->mode & SPI_LOOP));
writeb(conf8, rspi->base + RSPI_SPPCR);
/* Setup mode */
conf32 = FIELD_PREP(RSPI_SPCMD_CPOL, !!(spi->mode & SPI_CPOL));
conf32 |= FIELD_PREP(RSPI_SPCMD_CPHA, !!(spi->mode & SPI_CPHA));
@ -490,7 +499,7 @@ static int rzv2h_rspi_probe(struct platform_device *pdev)
}
controller->mode_bits = SPI_CPHA | SPI_CPOL | SPI_CS_HIGH |
SPI_LSB_FIRST;
SPI_LSB_FIRST | SPI_LOOP;
controller->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
controller->prepare_message = rzv2h_rspi_prepare_message;
controller->unprepare_message = rzv2h_rspi_unprepare_message;