[PATCH v3 1/4] i2c: tegra: implement slave mode
Andrey Danin
danindrey at mail.ru
Mon Jul 20 20:35:43 UTC 2015
Initialization code is based on NVEC driver.
There is a HW bug in AP20 that was also mentioned in kernel sources
for Toshiba AC100.
Signed-off-by: Andrey Danin <danindrey at mail.ru>
---
Changes for v3:
- handle 10-bit clients properly
Changes for v2:
- remove hack from tegra_i2c_clock_disable
- replace slave status helper functions with local variables
- add constant for default delay count value
- add 10-bit address support
- remove read_slave_start_delay init as zero
- don't reset controller during slave registration
- slave isr returns int instead of bool
- make status related variables in slave u32 instead of unsigned int
- enable i2c slave in Kconfig
- rebase on top of new i2c slave framework
- delay workaround was added from nvec
Signed-off-by: Andrey Danin <danindrey at mail.ru>
---
drivers/i2c/busses/Kconfig | 1 +
drivers/i2c/busses/i2c-tegra.c | 119 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 120 insertions(+)
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 0b798ae..3c02041 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -888,6 +888,7 @@ config I2C_SUN6I_P2WI
config I2C_TEGRA
tristate "NVIDIA Tegra internal I2C controller"
depends on ARCH_TEGRA
+ select I2C_SLAVE
help
If you say yes to this option, support will be included for the
I2C controller embedded in NVIDIA Tegra SOCs
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 78a3668..f6ecd28 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -42,8 +42,17 @@
#define I2C_SL_CNFG 0x020
#define I2C_SL_CNFG_NACK (1<<1)
#define I2C_SL_CNFG_NEWSL (1<<2)
+#define I2C_SL_RCVD 0x024
+#define I2C_SL_STATUS 0x028
+#define I2C_SL_ST_IRQ (1<<3)
+#define I2C_SL_ST_END_TRANS (1<<4)
+#define I2C_SL_ST_RCVD (1<<2)
+#define I2C_SL_ST_RNW (1<<1)
#define I2C_SL_ADDR1 0x02c
#define I2C_SL_ADDR2 0x030
+#define I2C_SL_ADDR2_TEN_BIT_MODE 1
+#define I2C_SL_DELAY_COUNT 0x03c
+#define I2C_SL_DELAY_COUNT_DEFAULT 0x1E
#define I2C_TX_FIFO 0x050
#define I2C_RX_FIFO 0x054
#define I2C_PACKET_TRANSFER_STATUS 0x058
@@ -125,6 +134,8 @@ enum msg_end_type {
* @clk_divisor_std_fast_mode: Clock divisor in standard/fast mode. It is
* applicable if there is no fast clock source i.e. single clock
* source.
+ * @slave_read_start_delay: Workaround for AP20 I2C Slave Controller bug. Delay
+ * before writing data byte into register I2C_SL_RCVD.
*/
struct tegra_i2c_hw_feature {
@@ -133,6 +144,7 @@ struct tegra_i2c_hw_feature {
bool has_single_clk_source;
int clk_divisor_hs_mode;
int clk_divisor_std_fast_mode;
+ int slave_read_start_delay;
};
/**
@@ -173,6 +185,7 @@ struct tegra_i2c_dev {
int msg_read;
u32 bus_clk_rate;
bool is_suspended;
+ struct i2c_client *slave;
};
static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val, unsigned long reg)
@@ -461,12 +474,78 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
return err;
}
+static void tegra_i2c_slave_write(struct tegra_i2c_dev *i2c_dev, u32 val)
+{
+ i2c_writel(i2c_dev, val, I2C_SL_RCVD);
+
+ /*
+ * TODO: A correct fix needs to be found for this.
+ *
+ * We experience less incomplete messages with this delay than without
+ * it, but we don't know why. Help is appreciated.
+ */
+ udelay(100);
+}
+
+static int tegra_i2c_slave_isr(int irq, struct tegra_i2c_dev *i2c_dev)
+{
+ u32 status;
+ u8 value;
+ u8 dummy;
+ u32 is_slave_irq, is_read, is_trans_start, is_trans_end;
+
+ if (!i2c_dev->slave || !i2c_dev->slave->slave_cb)
+ return -EINVAL;
+
+ status = i2c_readl(i2c_dev, I2C_SL_STATUS);
+
+ is_slave_irq = (status & I2C_SL_ST_IRQ);
+ is_read = (status & I2C_SL_ST_RNW);
+ is_trans_start = (status & I2C_SL_ST_RCVD);
+ is_trans_end = (status & I2C_SL_ST_END_TRANS);
+
+ if (!is_slave_irq)
+ return -EINVAL;
+
+ /* master sent stop */
+ if (is_trans_end) {
+ i2c_slave_event(i2c_dev->slave, I2C_SLAVE_STOP, &dummy);
+ if (!is_trans_start)
+ return 0;
+ }
+
+ if (is_read) {
+ /* i2c master reads data from us */
+ i2c_slave_event(i2c_dev->slave,
+ is_trans_start ? I2C_SLAVE_READ_REQUESTED
+ : I2C_SLAVE_READ_PROCESSED,
+ &value);
+ if (is_trans_start && i2c_dev->hw->slave_read_start_delay)
+ udelay(i2c_dev->hw->slave_read_start_delay);
+ tegra_i2c_slave_write(i2c_dev, value);
+ } else {
+ /* i2c master sends data to us */
+ value = i2c_readl(i2c_dev, I2C_SL_RCVD);
+ if (is_trans_start)
+ tegra_i2c_slave_write(i2c_dev, 0);
+ i2c_slave_event(i2c_dev->slave,
+ is_trans_start ? I2C_SLAVE_WRITE_REQUESTED
+ : I2C_SLAVE_WRITE_RECEIVED,
+ &value);
+ }
+
+ return 0;
+}
+
static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
{
u32 status;
const u32 status_err = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
struct tegra_i2c_dev *i2c_dev = dev_id;
+ if (!tegra_i2c_slave_isr(irq, i2c_dev))
+ return IRQ_HANDLED;
+
status = i2c_readl(i2c_dev, I2C_INT_STATUS);
if (status == 0) {
@@ -664,9 +743,48 @@ static u32 tegra_i2c_func(struct i2c_adapter *adap)
return ret;
}
+static int tegra_reg_slave(struct i2c_client *slave)
+{
+ struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(slave->adapter);
+ int addr2 = 0;
+
+ if (i2c_dev->slave)
+ return -EBUSY;
+
+ i2c_dev->slave = slave;
+
+ tegra_i2c_clock_enable(i2c_dev);
+
+ i2c_writel(i2c_dev, I2C_SL_CNFG_NEWSL, I2C_SL_CNFG);
+ i2c_writel(i2c_dev, I2C_SL_DELAY_COUNT_DEFAULT, I2C_SL_DELAY_COUNT);
+
+ if (slave->flags & I2C_CLIENT_TEN)
+ addr2 = (slave->addr >> 7) | I2C_SL_ADDR2_TEN_BIT_MODE;
+
+ i2c_writel(i2c_dev, slave->addr, I2C_SL_ADDR1);
+ i2c_writel(i2c_dev, addr2, I2C_SL_ADDR2);
+
+ return 0;
+}
+
+static int tegra_unreg_slave(struct i2c_client *slave)
+{
+ struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(slave->adapter);
+
+ WARN_ON(!i2c_dev->slave);
+
+ i2c_writel(i2c_dev, 0, I2C_SL_CNFG);
+
+ i2c_dev->slave = NULL;
+
+ return 0;
+}
+
static const struct i2c_algorithm tegra_i2c_algo = {
.master_xfer = tegra_i2c_xfer,
.functionality = tegra_i2c_func,
+ .reg_slave = tegra_reg_slave,
+ .unreg_slave = tegra_unreg_slave,
};
/* payload size is only 12 bit */
@@ -681,6 +799,7 @@ static const struct tegra_i2c_hw_feature tegra20_i2c_hw = {
.has_single_clk_source = false,
.clk_divisor_hs_mode = 3,
.clk_divisor_std_fast_mode = 0,
+ .slave_read_start_delay = 8,
};
static const struct tegra_i2c_hw_feature tegra30_i2c_hw = {
--
1.9.1
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