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spi: sh-msiof: Avoid writing to registers from spi_master.setup()

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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>
This commit is contained in:
Geert Uytterhoeven 2017-12-13 20:05:10 +01:00 committed by Mark Brown
parent 5d8e614f6c
commit 7ff0b53c40
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GPG Key ID: 24D68B725D5487D0
1 changed files with 24 additions and 11 deletions
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35
drivers/spi/spi-sh-msiof.c
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@ -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;
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;
}