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i2c/i2c_dw: extends to do multi-byte read requests

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This changes to request bytes that will fill the RX FIFO
instead of requesting byte one-by-one.

Change-Id: I30696c624c9f828818f6df9f1ee744a5bc515f27
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2016-01-12 10:25:32 -08:00 committed by Anas Nashif
parent 9b8acb7b26
commit 61ea58b6cf
2 changed files with 48 additions and 18 deletions
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65
drivers/i2c/i2c_dw.c
View file

@ -30,6 +30,8 @@
#include <errno.h>
#include <sys_io.h>
#include <misc/util.h>
#ifdef CONFIG_SHARED_IRQ
#include <shared_irq.h>
#endif
@ -57,6 +59,9 @@ static inline void _i2c_dw_data_ask(struct device *dev)
struct i2c_dw_rom_config const * const rom = dev->config->config_info;
struct i2c_dw_dev_config * const dw = dev->driver_data;
uint32_t data;
uint8_t tx_empty;
int8_t rx_empty;
uint8_t cnt;
volatile struct i2c_dw_registers * const regs =
(struct i2c_dw_registers *)rom->base_address;
@ -67,23 +72,45 @@ static inline void _i2c_dw_data_ask(struct device *dev)
return;
}
/* Tell controller to get another byte */
data = IC_DATA_CMD_CMD;
/* How many bytes we can actually ask */
rx_empty = (I2C_DW_FIFO_DEPTH - regs->ic_rxflr) - dw->rx_pending;
/* Send RESTART if needed */
if (dw->xfr_flags & I2C_MSG_RESTART) {
data |= IC_DATA_CMD_RESTART;
dw->xfr_flags &= ~(I2C_MSG_RESTART);
if (rx_empty < 0) {
/* RX FIFO expected to be full.
* So don't request any bytes, yet.
*/
return;
}
/* After receiving the last byte, send STOP if needed */
if ((dw->xfr_flags & I2C_MSG_STOP) && (dw->request_bytes == 1)) {
data |= IC_DATA_CMD_STOP;
/* How many empty slots in TX FIFO (as command queue) */
tx_empty = I2C_DW_FIFO_DEPTH - regs->ic_txflr;
/* Figure out how many bytes we can request */
cnt = min(I2C_DW_FIFO_DEPTH, dw->request_bytes);
cnt = min(min(tx_empty, rx_empty), cnt);
while (cnt > 0) {
/* Tell controller to get another byte */
data = IC_DATA_CMD_CMD;
/* Send RESTART if needed */
if (dw->xfr_flags & I2C_MSG_RESTART) {
data |= IC_DATA_CMD_RESTART;
dw->xfr_flags &= ~(I2C_MSG_RESTART);
}
/* After receiving the last byte, send STOP if needed */
if ((dw->xfr_flags & I2C_MSG_STOP)
&& (dw->request_bytes == 1)) {
data |= IC_DATA_CMD_STOP;
}
regs->ic_data_cmd.raw = data;
dw->rx_pending++;
dw->request_bytes--;
cnt--;
}
regs->ic_data_cmd.raw = data;
dw->request_bytes--;
}
static void _i2c_dw_data_read(struct device *dev)
@ -99,12 +126,11 @@ static void _i2c_dw_data_read(struct device *dev)
dw->xfr_buf++;
dw->xfr_len--;
dw->rx_pending--;
if (dw->xfr_len == 0) {
break;
}
_i2c_dw_data_ask(dev);
}
/* Nothing to receive anymore */
@ -369,9 +395,11 @@ static int _i2c_dw_setup(struct device *dev, uint16_t slave_address)
/* Set TX fifo threshold level.
* TX_EMPTY interrupt is triggered only when the
* TX FIFO is truly empty.
*
* TODO: threshold set to just enough for TX
* TX FIFO is truly empty. So that we can let
* the controller do the transfers for longer period
* before we need to fill the FIFO again. This may
* cause some pauses during transfers, but this keeps
* the device from interrupting often.
*/
regs->ic_tx_tl = 0;
@ -428,6 +456,7 @@ static int i2c_dw_transfer(struct device *dev,
dw->xfr_buf = cur_msg->buf;
dw->xfr_len = cur_msg->len;
dw->xfr_flags = cur_msg->flags;
dw->rx_pending = 0;
/* Need to RESTART if changing transfer direction */
if ((pflags & I2C_MSG_RW_MASK)

1
drivers/i2c/i2c_dw.h
View file

@ -116,6 +116,7 @@ struct i2c_dw_dev_config {
uint8_t *xfr_buf;
uint32_t xfr_len;
uint32_t rx_pending;
bool support_hs_mode;
uint16_t hcnt;