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Subject[PATCH 5.10 37/57] i2c: tegra: Create i2c_writesl_vi() to use with VI I2C for filling TX FIFO
Date
From: Sowjanya Komatineni <skomatineni@nvidia.com>

[ Upstream commit 2f3a0828d46166d4e7df227479ed31766ee67e4a ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/i2c/busses/i2c-tegra.c | 22 +++++++++++++++++++++-
1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 0727383f49402..8b113ae32dc71 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -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;
}
--
2.27.0


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