spi: atmel: Fix scheduling while atomic

A call to clk_get_rate appears to be called in the context of an interrupt,
cache the bus clock for the frequency calculations in transmission.

This fixes a 'BUG: scheduling while atomic' and
'WARNING: CPU: 0 PID: 777 at kernel/sched/core.c:2960 atmel_spi_unlock'

Signed-off-by: Ben Whitten <ben.whitten@lairdtech.com>
Signed-off-by: Steve deRosier <steve.derosier@lairdtech.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
index d3affa6afe7e..9fb00ac3ac2e 100644
--- a/drivers/spi/spi-atmel.c
+++ b/drivers/spi/spi-atmel.c
@@ -296,6 +296,7 @@ struct atmel_spi {
         int                     irq;
         struct clk              *clk;
         struct platform_device  *pdev;
+        unsigned long           spi_clk;
 
         struct spi_transfer     *current_transfer;
         int                     current_remaining_bytes;
@@ -865,7 +866,7 @@ static int atmel_spi_set_xfer_speed(struct atmel_spi *as,
         unsigned long           bus_hz;
 
         /* v1 chips start out at half the peripheral bus speed. */
-        bus_hz = clk_get_rate(as->clk);
+        bus_hz = as->spi_clk;
         if (!atmel_spi_is_v2(as))
                 bus_hz /= 2;
 
@@ -1634,6 +1635,9 @@ static int atmel_spi_probe(struct platform_device *pdev)
         ret = clk_prepare_enable(clk);
         if (ret)
                 goto out_free_irq;
+
+        as->spi_clk = clk_get_rate(clk);
+
         spi_writel(as, CR, SPI_BIT(SWRST));
         spi_writel(as, CR, SPI_BIT(SWRST)); /* AT91SAM9263 Rev B workaround */
         if (as->caps.has_wdrbt) {