Commit 2f3a0828 authored by Sowjanya Komatineni's avatar Sowjanya Komatineni Committed by Wolfram Sang
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i2c: tegra: Create i2c_writesl_vi() to use with VI I2C for filling TX FIFO 



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: default avatarSowjanya Komatineni <skomatineni@nvidia.com>
Reviewed-by: default avatarDmitry Osipenko <digetx@gmail.com>
Acked-by: default avatarThierry Reding <treding@nvidia.com>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
parent bc1c2048

drivers/i2c/busses/i2c-tegra.c

+21 −1
Original line number Diff line number Diff line
@@ -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)

{
@@ -811,6 +828,9 @@ 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;



		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;