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Date: Wed, 18 Sep 2013 14:13:39 -0400
From: Rhyland Klein <rklein@...dia.com>
To: Grant Likely <grant.likely@...retlab.ca>,
Laxman Dewangan <ldewangan@...dia.com>
CC: <spi-devel-general@...ts.sourceforge.net>,
<linux-kernel@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
Simon Glass <sjg@...omium.org>,
Olof Johansson <olof@...om.net>,
Rhyland Klein <rklein@...dia.com>
Subject: [IP REVIEW] spi/tegra114: Correct support for cs_change
The tegra114 driver wasn't currently handling the cs_change functionality.
It is meant to invert normal behavior, and we were only using it to possibly
delay at the end of a transfer.
This patch modifies the logic so that the cs state will be toggled after
every individual transfer or NOT toggled at the end of the last transfer
if cs_change is set in that transfer struct.
Also, this builds in logic so that if a different device tries to start
a transfer while CS is active from a different device, it will abort the
previous transfer and start a new one for the new device.
This work was based on the spi-atmel driver.
Signed-off-by: Rhyland Klein <rklein@...dia.com>
---
drivers/spi/spi-tegra114.c | 59 ++++++++++++++++++++++++++++++++++++++------
1 file changed, 52 insertions(+), 7 deletions(-)
diff --git a/drivers/spi/spi-tegra114.c b/drivers/spi/spi-tegra114.c
index 145dd43..a9973de 100644
--- a/drivers/spi/spi-tegra114.c
+++ b/drivers/spi/spi-tegra114.c
@@ -182,6 +182,7 @@ struct tegra_spi_data {
u32 cur_speed;
struct spi_device *cur_spi;
+ struct spi_device *cs_control;
unsigned cur_pos;
unsigned cur_len;
unsigned words_per_32bit;
@@ -717,7 +718,12 @@ static int tegra_spi_start_transfer_one(struct spi_device *spi,
else if (req_mode == SPI_MODE_3)
command1 |= SPI_CONTROL_MODE_3;
- tegra_spi_writel(tspi, command1, SPI_COMMAND1);
+ if (tspi->cs_control) {
+ if (tspi->cs_control != spi)
+ tegra_spi_writel(tspi, command1, SPI_COMMAND1);
+ tspi->cs_control = NULL;
+ } else
+ tegra_spi_writel(tspi, command1, SPI_COMMAND1);
command1 |= SPI_CS_SW_HW;
if (spi->mode & SPI_CS_HIGH)
@@ -732,6 +738,9 @@ static int tegra_spi_start_transfer_one(struct spi_device *spi,
command1 |= SPI_BIT_LENGTH(bits_per_word - 1);
}
+ if (t->len == 0 && !t->tx_buf && !t->rx_buf)
+ return 0;
+
if (tspi->is_packed)
command1 |= SPI_PACKED;
@@ -803,6 +812,17 @@ static int tegra_spi_setup(struct spi_device *spi)
return 0;
}
+static void tegra_spi_transfer_delay(int delay)
+{
+ if (!delay)
+ return;
+
+ if (delay >= 1000)
+ mdelay(delay / 1000);
+
+ udelay(delay % 1000);
+}
+
static int tegra_spi_transfer_one_message(struct spi_master *master,
struct spi_message *msg)
{
@@ -812,6 +832,7 @@ static int tegra_spi_transfer_one_message(struct spi_master *master,
struct spi_transfer *xfer;
struct spi_device *spi = msg->spi;
int ret;
+ bool skip = false;
msg->status = 0;
msg->actual_length = 0;
@@ -819,13 +840,20 @@ static int tegra_spi_transfer_one_message(struct spi_master *master,
single_xfer = list_is_singular(&msg->transfers);
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
INIT_COMPLETION(tspi->xfer_completion);
+
ret = tegra_spi_start_transfer_one(spi, xfer,
is_first_msg, single_xfer);
if (ret < 0) {
dev_err(tspi->dev,
"spi can not start transfer, err %d\n", ret);
- goto exit;
+ goto complete_xfer;
+ }
+
+ if (xfer->len == 0 && !xfer->tx_buf && !xfer->rx_buf) {
+ skip = true;
+ goto complete_xfer;
}
+
is_first_msg = false;
ret = wait_for_completion_timeout(&tspi->xfer_completion,
SPI_DMA_TIMEOUT);
@@ -833,24 +861,41 @@ static int tegra_spi_transfer_one_message(struct spi_master *master,
dev_err(tspi->dev,
"spi trasfer timeout, err %d\n", ret);
ret = -EIO;
- goto exit;
+ goto complete_xfer;
}
if (tspi->tx_status || tspi->rx_status) {
dev_err(tspi->dev, "Error in Transfer\n");
ret = -EIO;
- goto exit;
+ goto complete_xfer;
}
msg->actual_length += xfer->len;
- if (xfer->cs_change && xfer->delay_usecs) {
+
+complete_xfer:
+ if (ret < 0 || skip) {
tegra_spi_writel(tspi, tspi->def_command1_reg,
SPI_COMMAND1);
- udelay(xfer->delay_usecs);
+ tegra_spi_transfer_delay(xfer->delay_usecs);
+ goto exit;
+ } else if (msg->transfers.prev == &xfer->transfer_list) {
+ /* This is the last transfer in message */
+ if (xfer->cs_change)
+ tspi->cs_control = spi;
+ else {
+ tegra_spi_writel(tspi, tspi->def_command1_reg,
+ SPI_COMMAND1);
+ tegra_spi_transfer_delay(xfer->delay_usecs);
+ }
+ } else if (xfer->cs_change) {
+ tegra_spi_writel(tspi, tspi->def_command1_reg,
+ SPI_COMMAND1);
+ tegra_spi_transfer_delay(xfer->delay_usecs);
}
+
}
ret = 0;
exit:
- tegra_spi_writel(tspi, tspi->def_command1_reg, SPI_COMMAND1);
+
msg->status = ret;
spi_finalize_current_message(master);
return ret;
--
1.7.9.5
--
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