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Subject[PATCH AUTOSEL for 4.15 17/78] spi: sh-msiof: Avoid writing to registers from spi_master.setup()
Date
From: Geert Uytterhoeven <geert+renesas@glider.be>

[ Upstream commit 7ff0b53c4051145d1cf992d2f60987e6447eed4f ]

The spi_master.setup() callback must not change configuration registers,
as that could corrupt I/O that is in progress for other SPI slaves.

The only exception is the configuration of the native chip select
polarity in SPI master mode, as a wrong chip select polarity will cause
havoc during all future transfers to any other SPI slave.

Hence stop writing to registers in sh_msiof_spi_setup(), unless it is
the first call for a controller using a native chip select, or unless
native chip select polarity has changed (note that you'll loose anyway
if I/O is in progress). Even then, only do what is strictly necessary,
instead of calling sh_msiof_spi_set_pin_regs().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/spi/spi-sh-msiof.c | 35 ++++++++++++++++++++++++-----------
1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index fcd261f98b9f..bf34e9b238af 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -55,6 +55,8 @@ struct sh_msiof_spi_priv {
void *rx_dma_page;
dma_addr_t tx_dma_addr;
dma_addr_t rx_dma_addr;
+ bool native_cs_inited;
+ bool native_cs_high;
bool slave_aborted;
};

@@ -528,8 +530,7 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
{
struct device_node *np = spi->master->dev.of_node;
struct sh_msiof_spi_priv *p = spi_master_get_devdata(spi->master);
-
- pm_runtime_get_sync(&p->pdev->dev);
+ u32 clr, set, tmp;

if (!np) {
/*
@@ -539,19 +540,31 @@ static int sh_msiof_spi_setup(struct spi_device *spi)
spi->cs_gpio = (uintptr_t)spi->controller_data;
}

- /* Configure pins before deasserting CS */
- sh_msiof_spi_set_pin_regs(p, !!(spi->mode & SPI_CPOL),
- !!(spi->mode & SPI_CPHA),
- !!(spi->mode & SPI_3WIRE),
- !!(spi->mode & SPI_LSB_FIRST),
- !!(spi->mode & SPI_CS_HIGH));
-
- if (spi->cs_gpio >= 0)
+ if (spi->cs_gpio >= 0) {
gpio_set_value(spi->cs_gpio, !(spi->mode & SPI_CS_HIGH));
+ return 0;
+ }

+ if (spi_controller_is_slave(p->master))
+ return 0;

- pm_runtime_put(&p->pdev->dev);
+ if (p->native_cs_inited &&
+ (p->native_cs_high == !!(spi->mode & SPI_CS_HIGH)))
+ return 0;

+ /* Configure native chip select mode/polarity early */
+ clr = MDR1_SYNCMD_MASK;
+ set = MDR1_TRMD | TMDR1_PCON | MDR1_SYNCMD_SPI;
+ if (spi->mode & SPI_CS_HIGH)
+ clr |= BIT(MDR1_SYNCAC_SHIFT);
+ else
+ set |= BIT(MDR1_SYNCAC_SHIFT);
+ pm_runtime_get_sync(&p->pdev->dev);
+ tmp = sh_msiof_read(p, TMDR1) & ~clr;
+ sh_msiof_write(p, TMDR1, tmp | set);
+ pm_runtime_put(&p->pdev->dev);
+ p->native_cs_high = spi->mode & SPI_CS_HIGH;
+ p->native_cs_inited = true;
return 0;
}

--
2.14.1
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