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Message-Id: <20221226142326.8111-2-i.bornyakov@metrotek.ru>
Date: Mon, 26 Dec 2022 17:23:24 +0300
From: Ivan Bornyakov <i.bornyakov@...rotek.ru>
To: Conor Dooley <conor.dooley@...rochip.com>,
Moritz Fischer <mdf@...nel.org>, Wu Hao <hao.wu@...el.com>,
Xu Yilun <yilun.xu@...el.com>, Tom Rix <trix@...hat.com>
Cc: Ivan Bornyakov <i.bornyakov@...rotek.ru>,
linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org,
system@...rotek.ru
Subject: [PATCH v2 1/3] fpga: microchip-spi: move SPI I/O buffers out of stack
As spi-summary doc says:
> I/O buffers use the usual Linux rules, and must be DMA-safe.
> You'd normally allocate them from the heap or free page pool.
> Don't use the stack, or anything that's declared "static".
Replace spi_write() with spi_write_then_read(), which is dma-safe for
on-stack buffers. Use allocated buffers for transfers used in
spi_sync_transfer().
Although everything works OK with stack-located I/O buffers, better
follow the doc to be safe.
Fixes: 5f8d4a900830 ("fpga: microchip-spi: add Microchip MPF FPGA manager")
Signed-off-by: Ivan Bornyakov <i.bornyakov@...rotek.ru>
---
drivers/fpga/microchip-spi.c | 93 ++++++++++++++++++------------------
1 file changed, 47 insertions(+), 46 deletions(-)
diff --git a/drivers/fpga/microchip-spi.c b/drivers/fpga/microchip-spi.c
index 7436976ea904..e72fedd93a27 100644
--- a/drivers/fpga/microchip-spi.c
+++ b/drivers/fpga/microchip-spi.c
@@ -42,46 +42,55 @@
struct mpf_priv {
struct spi_device *spi;
bool program_mode;
+ u8 tx __aligned(ARCH_KMALLOC_MINALIGN);
+ u8 rx __aligned(ARCH_KMALLOC_MINALIGN);
};
-static int mpf_read_status(struct spi_device *spi)
+static int mpf_read_status(struct mpf_priv *priv)
{
- u8 status = 0, status_command = MPF_SPI_READ_STATUS;
- struct spi_transfer xfers[2] = { 0 };
- int ret;
-
/*
* HW status is returned on MISO in the first byte after CS went
* active. However, first reading can be inadequate, so we submit
* two identical SPI transfers and use result of the later one.
*/
- xfers[0].tx_buf = &status_command;
- xfers[1].tx_buf = &status_command;
- xfers[0].rx_buf = &status;
- xfers[1].rx_buf = &status;
- xfers[0].len = 1;
- xfers[1].len = 1;
- xfers[0].cs_change = 1;
+ struct spi_transfer xfers[2] = {
+ {
+ .tx_buf = &priv->tx,
+ .rx_buf = &priv->rx,
+ .len = 1,
+ .cs_change = 1,
+ }, {
+ .tx_buf = &priv->tx,
+ .rx_buf = &priv->rx,
+ .len = 1,
+ },
+ };
+ u8 status;
+ int ret;
+
+ priv->tx = MPF_SPI_READ_STATUS;
+
+ ret = spi_sync_transfer(priv->spi, xfers, 2);
+ if (ret)
+ return ret;
- ret = spi_sync_transfer(spi, xfers, 2);
+ status = priv->rx;
if ((status & MPF_STATUS_SPI_VIOLATION) ||
(status & MPF_STATUS_SPI_ERROR))
- ret = -EIO;
+ return -EIO;
- return ret ? : status;
+ return status;
}
static enum fpga_mgr_states mpf_ops_state(struct fpga_manager *mgr)
{
struct mpf_priv *priv = mgr->priv;
- struct spi_device *spi;
bool program_mode;
int status;
- spi = priv->spi;
program_mode = priv->program_mode;
- status = mpf_read_status(spi);
+ status = mpf_read_status(priv);
if (!program_mode && !status)
return FPGA_MGR_STATE_OPERATING;
@@ -186,12 +195,12 @@ static int mpf_ops_parse_header(struct fpga_manager *mgr,
}
/* Poll HW status until busy bit is cleared and mask bits are set. */
-static int mpf_poll_status(struct spi_device *spi, u8 mask)
+static int mpf_poll_status(struct mpf_priv *priv, u8 mask)
{
int status, retries = MPF_STATUS_POLL_RETRIES;
while (retries--) {
- status = mpf_read_status(spi);
+ status = mpf_read_status(priv);
if (status < 0)
return status;
@@ -205,32 +214,32 @@ static int mpf_poll_status(struct spi_device *spi, u8 mask)
return -EBUSY;
}
-static int mpf_spi_write(struct spi_device *spi, const void *buf, size_t buf_size)
+static int mpf_spi_write(struct mpf_priv *priv, const void *buf, size_t buf_size)
{
- int status = mpf_poll_status(spi, 0);
+ int status = mpf_poll_status(priv, 0);
if (status < 0)
return status;
- return spi_write(spi, buf, buf_size);
+ return spi_write_then_read(priv->spi, buf, buf_size, NULL, 0);
}
-static int mpf_spi_write_then_read(struct spi_device *spi,
+static int mpf_spi_write_then_read(struct mpf_priv *priv,
const void *txbuf, size_t txbuf_size,
void *rxbuf, size_t rxbuf_size)
{
const u8 read_command[] = { MPF_SPI_READ_DATA };
int ret;
- ret = mpf_spi_write(spi, txbuf, txbuf_size);
+ ret = mpf_spi_write(priv, txbuf, txbuf_size);
if (ret)
return ret;
- ret = mpf_poll_status(spi, MPF_STATUS_READY);
+ ret = mpf_poll_status(priv, MPF_STATUS_READY);
if (ret < 0)
return ret;
- return spi_write_then_read(spi, read_command, sizeof(read_command),
+ return spi_write_then_read(priv->spi, read_command, sizeof(read_command),
rxbuf, rxbuf_size);
}
@@ -242,7 +251,6 @@ static int mpf_ops_write_init(struct fpga_manager *mgr,
const u8 isc_en_command[] = { MPF_SPI_ISC_ENABLE };
struct mpf_priv *priv = mgr->priv;
struct device *dev = &mgr->dev;
- struct spi_device *spi;
u32 isc_ret = 0;
int ret;
@@ -251,9 +259,7 @@ static int mpf_ops_write_init(struct fpga_manager *mgr,
return -EOPNOTSUPP;
}
- spi = priv->spi;
-
- ret = mpf_spi_write_then_read(spi, isc_en_command, sizeof(isc_en_command),
+ ret = mpf_spi_write_then_read(priv, isc_en_command, sizeof(isc_en_command),
&isc_ret, sizeof(isc_ret));
if (ret || isc_ret) {
dev_err(dev, "Failed to enable ISC: spi_ret %d, isc_ret %u\n",
@@ -261,7 +267,7 @@ static int mpf_ops_write_init(struct fpga_manager *mgr,
return -EFAULT;
}
- ret = mpf_spi_write(spi, program_mode, sizeof(program_mode));
+ ret = mpf_spi_write(priv, program_mode, sizeof(program_mode));
if (ret) {
dev_err(dev, "Failed to enter program mode: %d\n", ret);
return ret;
@@ -274,11 +280,9 @@ static int mpf_ops_write_init(struct fpga_manager *mgr,
static int mpf_ops_write(struct fpga_manager *mgr, const char *buf, size_t count)
{
- u8 spi_frame_command[] = { MPF_SPI_FRAME };
struct spi_transfer xfers[2] = { 0 };
struct mpf_priv *priv = mgr->priv;
struct device *dev = &mgr->dev;
- struct spi_device *spi;
int ret, i;
if (count % MPF_SPI_FRAME_SIZE) {
@@ -287,18 +291,18 @@ static int mpf_ops_write(struct fpga_manager *mgr, const char *buf, size_t count
return -EINVAL;
}
- spi = priv->spi;
-
- xfers[0].tx_buf = spi_frame_command;
- xfers[0].len = sizeof(spi_frame_command);
+ xfers[0].tx_buf = &priv->tx;
+ xfers[0].len = 1;
for (i = 0; i < count / MPF_SPI_FRAME_SIZE; i++) {
xfers[1].tx_buf = buf + i * MPF_SPI_FRAME_SIZE;
xfers[1].len = MPF_SPI_FRAME_SIZE;
- ret = mpf_poll_status(spi, 0);
- if (ret >= 0)
- ret = spi_sync_transfer(spi, xfers, ARRAY_SIZE(xfers));
+ ret = mpf_poll_status(priv, 0);
+ if (ret >= 0) {
+ priv->tx = MPF_SPI_FRAME;
+ ret = spi_sync_transfer(priv->spi, xfers, ARRAY_SIZE(xfers));
+ }
if (ret) {
dev_err(dev, "Failed to write bitstream frame %d/%zu\n",
@@ -317,12 +321,9 @@ static int mpf_ops_write_complete(struct fpga_manager *mgr,
const u8 release_command[] = { MPF_SPI_RELEASE };
struct mpf_priv *priv = mgr->priv;
struct device *dev = &mgr->dev;
- struct spi_device *spi;
int ret;
- spi = priv->spi;
-
- ret = mpf_spi_write(spi, isc_dis_command, sizeof(isc_dis_command));
+ ret = mpf_spi_write(priv, isc_dis_command, sizeof(isc_dis_command));
if (ret) {
dev_err(dev, "Failed to disable ISC: %d\n", ret);
return ret;
@@ -330,7 +331,7 @@ static int mpf_ops_write_complete(struct fpga_manager *mgr,
usleep_range(1000, 2000);
- ret = mpf_spi_write(spi, release_command, sizeof(release_command));
+ ret = mpf_spi_write(priv, release_command, sizeof(release_command));
if (ret) {
dev_err(dev, "Failed to exit program mode: %d\n", ret);
return ret;
--
2.38.2
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