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Diffstat (limited to 'drivers/i2c/busses/i2c-img-scb.c')
-rw-r--r--drivers/i2c/busses/i2c-img-scb.c92
1 files changed, 67 insertions, 25 deletions
diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c
index 3795fe130ef2..379ef9c31664 100644
--- a/drivers/i2c/busses/i2c-img-scb.c
+++ b/drivers/i2c/busses/i2c-img-scb.c
@@ -151,10 +151,11 @@
#define INT_FIFO_EMPTYING BIT(12)
#define INT_TRANSACTION_DONE BIT(15)
#define INT_SLAVE_EVENT BIT(16)
+#define INT_MASTER_HALTED BIT(17)
#define INT_TIMING BIT(18)
+#define INT_STOP_DETECTED BIT(19)
#define INT_FIFO_FULL_FILLING (INT_FIFO_FULL | INT_FIFO_FILLING)
-#define INT_FIFO_EMPTY_EMPTYING (INT_FIFO_EMPTY | INT_FIFO_EMPTYING)
/* Level interrupts need clearing after handling instead of before */
#define INT_LEVEL 0x01e00
@@ -177,7 +178,8 @@
INT_FIFO_FULL | \
INT_FIFO_FILLING | \
INT_FIFO_EMPTY | \
- INT_FIFO_EMPTYING)
+ INT_MASTER_HALTED | \
+ INT_STOP_DETECTED)
#define INT_ENABLE_MASK_WAITSTOP (INT_SLAVE_EVENT | \
INT_ADDR_ACK_ERR | \
@@ -511,7 +513,17 @@ static void img_i2c_soft_reset(struct img_i2c *i2c)
SCB_CONTROL_CLK_ENABLE | SCB_CONTROL_SOFT_RESET);
}
-/* enable or release transaction halt for control of repeated starts */
+/*
+ * Enable or release transaction halt for control of repeated starts.
+ * In version 3.3 of the IP when transaction halt is set, an interrupt
+ * will be generated after each byte of a transfer instead of after
+ * every transfer but before the stop bit.
+ * Due to this behaviour we have to be careful that every time we
+ * release the transaction halt we have to re-enable it straight away
+ * so that we only process a single byte, not doing so will result in
+ * all remaining bytes been processed and a stop bit being issued,
+ * which will prevent us having a repeated start.
+ */
static void img_i2c_transaction_halt(struct img_i2c *i2c, bool t_halt)
{
u32 val;
@@ -580,7 +592,6 @@ static void img_i2c_read(struct img_i2c *i2c)
img_i2c_writel(i2c, SCB_READ_ADDR_REG, i2c->msg.addr);
img_i2c_writel(i2c, SCB_READ_COUNT_REG, i2c->msg.len);
- img_i2c_transaction_halt(i2c, false);
mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
}
@@ -594,7 +605,6 @@ static void img_i2c_write(struct img_i2c *i2c)
img_i2c_writel(i2c, SCB_WRITE_ADDR_REG, i2c->msg.addr);
img_i2c_writel(i2c, SCB_WRITE_COUNT_REG, i2c->msg.len);
- img_i2c_transaction_halt(i2c, false);
mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
img_i2c_write_fifo(i2c);
@@ -750,7 +760,9 @@ static unsigned int img_i2c_atomic(struct img_i2c *i2c,
next_cmd = CMD_RET_ACK;
break;
case CMD_RET_ACK:
- if (i2c->line_status & LINESTAT_ACK_DET) {
+ if (i2c->line_status & LINESTAT_ACK_DET ||
+ (i2c->line_status & LINESTAT_NACK_DET &&
+ i2c->msg.flags & I2C_M_IGNORE_NAK)) {
if (i2c->msg.len == 0) {
next_cmd = CMD_GEN_STOP;
} else if (i2c->msg.flags & I2C_M_RD) {
@@ -858,34 +870,42 @@ static unsigned int img_i2c_auto(struct img_i2c *i2c,
/* Enable transaction halt on start bit */
if (!i2c->last_msg && line_status & LINESTAT_START_BIT_DET) {
- img_i2c_transaction_halt(i2c, true);
+ img_i2c_transaction_halt(i2c, !i2c->last_msg);
/* we're no longer interested in the slave event */
i2c->int_enable &= ~INT_SLAVE_EVENT;
}
mod_timer(&i2c->check_timer, jiffies + msecs_to_jiffies(1));
+ if (int_status & INT_STOP_DETECTED) {
+ /* Drain remaining data in FIFO and complete transaction */
+ if (i2c->msg.flags & I2C_M_RD)
+ img_i2c_read_fifo(i2c);
+ return ISR_COMPLETE(0);
+ }
+
if (i2c->msg.flags & I2C_M_RD) {
- if (int_status & INT_FIFO_FULL_FILLING) {
+ if (int_status & (INT_FIFO_FULL_FILLING | INT_MASTER_HALTED)) {
img_i2c_read_fifo(i2c);
if (i2c->msg.len == 0)
return ISR_WAITSTOP;
}
} else {
- if (int_status & INT_FIFO_EMPTY_EMPTYING) {
- /*
- * The write fifo empty indicates that we're in the
- * last byte so it's safe to start a new write
- * transaction without losing any bytes from the
- * previous one.
- * see 2.3.7 Repeated Start Transactions.
- */
+ if (int_status & (INT_FIFO_EMPTY | INT_MASTER_HALTED)) {
if ((int_status & INT_FIFO_EMPTY) &&
i2c->msg.len == 0)
return ISR_WAITSTOP;
img_i2c_write_fifo(i2c);
}
}
+ if (int_status & INT_MASTER_HALTED) {
+ /*
+ * Release and then enable transaction halt, to
+ * allow only a single byte to proceed.
+ */
+ img_i2c_transaction_halt(i2c, false);
+ img_i2c_transaction_halt(i2c, !i2c->last_msg);
+ }
return 0;
}
@@ -1017,20 +1037,23 @@ static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
return -EIO;
for (i = 0; i < num; i++) {
- if (likely(msgs[i].len))
- continue;
/*
* 0 byte reads are not possible because the slave could try
* and pull the data line low, preventing a stop bit.
*/
- if (unlikely(msgs[i].flags & I2C_M_RD))
+ if (!msgs[i].len && msgs[i].flags & I2C_M_RD)
return -EIO;
/*
* 0 byte writes are possible and used for probing, but we
* cannot do them in automatic mode, so use atomic mode
* instead.
+ *
+ * Also, the I2C_M_IGNORE_NAK mode can only be implemented
+ * in atomic mode.
*/
- atomic = true;
+ if (!msgs[i].len ||
+ (msgs[i].flags & I2C_M_IGNORE_NAK))
+ atomic = true;
}
ret = clk_prepare_enable(i2c->scb_clk);
@@ -1069,12 +1092,31 @@ static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0);
img_i2c_writel(i2c, SCB_CLEAR_REG, ~0);
- if (atomic)
+ if (atomic) {
img_i2c_atomic_start(i2c);
- else if (msg->flags & I2C_M_RD)
- img_i2c_read(i2c);
- else
- img_i2c_write(i2c);
+ } else {
+ /*
+ * Enable transaction halt if not the last message in
+ * the queue so that we can control repeated starts.
+ */
+ img_i2c_transaction_halt(i2c, !i2c->last_msg);
+
+ if (msg->flags & I2C_M_RD)
+ img_i2c_read(i2c);
+ else
+ img_i2c_write(i2c);
+
+ /*
+ * Release and then enable transaction halt, to
+ * allow only a single byte to proceed.
+ * This doesn't have an effect on the initial transfer
+ * but will allow the following transfers to start
+ * processing if the previous transfer was marked as
+ * complete while the i2c block was halted.
+ */
+ img_i2c_transaction_halt(i2c, false);
+ img_i2c_transaction_halt(i2c, !i2c->last_msg);
+ }
spin_unlock_irqrestore(&i2c->lock, flags);
time_left = wait_for_completion_timeout(&i2c->msg_complete,
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.