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i2c: tegra: Create i2c_writesl_vi() to use with VI I2C for filling TX FIFO

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VI I2C controller has known hardware bug where immediate multiple
writes to TX_FIFO register gets stuck.

Recommended software work around is to read I2C register after
each write to TX_FIFO register to flush out the data.

This patch implements this work around for VI I2C controller.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Sowjanya Komatineni 2021-01-12 11:02:41 -08:00 committed by Wolfram Sang
parent bc1c2048ab
commit 2f3a0828d4
1 changed files with 21 additions and 1 deletions
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22
drivers/i2c/busses/i2c-tegra.c
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@ -326,6 +326,8 @@ static void i2c_writel(struct tegra_i2c_dev *i2c_dev, u32 val, unsigned int reg)
/* read back register to make sure that register writes completed */
if (reg != I2C_TX_FIFO)
readl_relaxed(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
else if (i2c_dev->is_vi)
readl_relaxed(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, I2C_INT_STATUS));
}
static u32 i2c_readl(struct tegra_i2c_dev *i2c_dev, unsigned int reg)
@ -339,6 +341,21 @@ static void i2c_writesl(struct tegra_i2c_dev *i2c_dev, void *data,
writesl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg), data, len);
}
static void i2c_writesl_vi(struct tegra_i2c_dev *i2c_dev, void *data,
unsigned int reg, unsigned int len)
{
u32 *data32 = data;
/*
* VI I2C controller has known hardware bug where writes get stuck
* when immediate multiple writes happen to TX_FIFO register.
* Recommended software work around is to read I2C register after
* each write to TX_FIFO register to flush out the data.
*/
while (len--)
i2c_writel(i2c_dev, *data32++, reg);
}
static void i2c_readsl(struct tegra_i2c_dev *i2c_dev, void *data,
unsigned int reg, unsigned int len)
{
@ -811,7 +828,10 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
i2c_dev->msg_buf_remaining = buf_remaining;
i2c_dev->msg_buf = buf + words_to_transfer * BYTES_PER_FIFO_WORD;
i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
if (i2c_dev->is_vi)
i2c_writesl_vi(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
else
i2c_writesl(i2c_dev, buf, I2C_TX_FIFO, words_to_transfer);
buf += words_to_transfer * BYTES_PER_FIFO_WORD;
}