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i2c: tegra: Add de-bounce cycles.

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This enables debouncing of the I2C lines. The debounce period is
2 * the debounce register field value, in terms of the I2C block's main
clock. The Tegra TRM indicates that a setting yielding >50nS is
desirable. Hence, a setting of 2 => 4 clocks @ 72MHz => ~55nS.

Signed-off-by: Ken Radtke <kradtke@nvidia.com>
[swarren: Added commit description body,
 Fixed 80-column limit, Reverted file permission change]
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
This commit is contained in:
Jay Cheng 2011-04-25 15:32:27 -06:00 committed by Ben Dooks
parent 2078cf3b22
commit 40abcf7723
1 changed files with 3 additions and 1 deletions
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4
drivers/i2c/busses/i2c-tegra.c
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@ -35,6 +35,7 @@
#define BYTES_PER_FIFO_WORD 4
#define I2C_CNFG 0x000
#define I2C_CNFG_DEBOUNCE_CNT_SHIFT 12
#define I2C_CNFG_PACKET_MODE_EN (1<<10)
#define I2C_CNFG_NEW_MASTER_FSM (1<<11)
#define I2C_STATUS 0x01C
@ -328,7 +329,8 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
if (i2c_dev->is_dvc)
tegra_dvc_init(i2c_dev);
val = I2C_CNFG_NEW_MASTER_FSM | I2C_CNFG_PACKET_MODE_EN;
val = I2C_CNFG_NEW_MASTER_FSM | I2C_CNFG_PACKET_MODE_EN |
(0x2 << I2C_CNFG_DEBOUNCE_CNT_SHIFT);
i2c_writel(i2c_dev, val, I2C_CNFG);
i2c_writel(i2c_dev, 0, I2C_INT_MASK);
clk_set_rate(i2c_dev->clk, i2c_dev->bus_clk_rate * 8);