spi: spi-bcm2835: Fix deadlock
The bcm2835_spi_transfer_one function can create a deadlock
if it is called while another thread already has the
CCF lock.
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Fixes: f8043872e796 ("spi: add driver for BCM2835")
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210716210245.13240-2-alexandru.tachici@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 5f8771f..775c0bf 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -83,6 +83,7 @@
* struct bcm2835_spi - BCM2835 SPI controller
* @regs: base address of register map
* @clk: core clock, divided to calculate serial clock
+ * @clk_hz: core clock cached speed
* @irq: interrupt, signals TX FIFO empty or RX FIFO ¾ full
* @tfr: SPI transfer currently processed
* @ctlr: SPI controller reverse lookup
@@ -116,6 +117,7 @@
struct bcm2835_spi {
void __iomem *regs;
struct clk *clk;
+ unsigned long clk_hz;
int irq;
struct spi_transfer *tfr;
struct spi_controller *ctlr;
@@ -1045,19 +1047,18 @@
{
struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
struct bcm2835_spidev *slv = spi_get_ctldata(spi);
- unsigned long spi_hz, clk_hz, cdiv;
+ unsigned long spi_hz, cdiv;
unsigned long hz_per_byte, byte_limit;
u32 cs = slv->prepare_cs;
/* set clock */
spi_hz = tfr->speed_hz;
- clk_hz = clk_get_rate(bs->clk);
- if (spi_hz >= clk_hz / 2) {
+ if (spi_hz >= bs->clk_hz / 2) {
cdiv = 2; /* clk_hz/2 is the fastest we can go */
} else if (spi_hz) {
/* CDIV must be a multiple of two */
- cdiv = DIV_ROUND_UP(clk_hz, spi_hz);
+ cdiv = DIV_ROUND_UP(bs->clk_hz, spi_hz);
cdiv += (cdiv % 2);
if (cdiv >= 65536)
@@ -1065,7 +1066,7 @@
} else {
cdiv = 0; /* 0 is the slowest we can go */
}
- tfr->effective_speed_hz = cdiv ? (clk_hz / cdiv) : (clk_hz / 65536);
+ tfr->effective_speed_hz = cdiv ? (bs->clk_hz / cdiv) : (bs->clk_hz / 65536);
bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
/* handle all the 3-wire mode */
@@ -1354,6 +1355,7 @@
return bs->irq ? bs->irq : -ENODEV;
clk_prepare_enable(bs->clk);
+ bs->clk_hz = clk_get_rate(bs->clk);
err = bcm2835_dma_init(ctlr, &pdev->dev, bs);
if (err)
