1 files changed, 43 insertions, 1 deletions

diff --git a/drivers/spi/spi-ath79.c b/drivers/spi/spi-ath79.c
index 9a5d7791c5fb..e02528244451 100644
--- a/drivers/spi/spi-ath79.c
+++ b/drivers/spi/spi-ath79.c
@@ -24,17 +24,24 @@
 #include <linux/spi/spi_bitbang.h>
 #include <linux/bitops.h>
 #include <linux/gpio.h>
+#include <linux/clk.h>
+#include <linux/err.h>
 
 #include <asm/mach-ath79/ar71xx_regs.h>
 #include <asm/mach-ath79/ath79_spi_platform.h>
 
 #define DRV_NAME        "ath79-spi"
 
+#define ATH79_SPI_RRW_DELAY_FACTOR      12000
+#define MHZ                             (1000 * 1000)
+
 struct ath79_spi {
         struct spi_bitbang      bitbang;
         u32                     ioc_base;
         u32                     reg_ctrl;
         void __iomem            *base;
+        struct clk              *clk;
+        unsigned                rrw_delay;
 };
 
 static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
@@ -52,6 +59,12 @@ static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
         return spi_master_get_devdata(spi->master);
 }
 
+static inline void ath79_spi_delay(struct ath79_spi *sp, unsigned nsecs)
+{
+        if (nsecs > sp->rrw_delay)
+                ndelay(nsecs - sp->rrw_delay);
+}
+
 static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
 {
         struct ath79_spi *sp = ath79_spidev_to_sp(spi);
@@ -184,7 +197,9 @@ static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 
                 /* setup MSB (to slave) on trailing edge */
                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
+                ath79_spi_delay(sp, nsecs);
                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
+                ath79_spi_delay(sp, nsecs);
 
                 word <<= 1;
         }
@@ -198,6 +213,7 @@ static int ath79_spi_probe(struct platform_device *pdev)
         struct ath79_spi *sp;
         struct ath79_spi_platform_data *pdata;
         struct resource *r;
+        unsigned long rate;
         int ret;
 
         master = spi_alloc_master(&pdev->dev, sizeof(*sp));
@@ -236,12 +252,36 @@ static int ath79_spi_probe(struct platform_device *pdev)
                 goto err_put_master;
         }
 
+        sp->clk = clk_get(&pdev->dev, "ahb");
+        if (IS_ERR(sp->clk)) {
+                ret = PTR_ERR(sp->clk);
+                goto err_unmap;
+        }
+
+        ret = clk_enable(sp->clk);
+        if (ret)
+                goto err_clk_put;
+
+        rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
+        if (!rate) {
+                ret = -EINVAL;
+                goto err_clk_disable;
+        }
+
+        sp->rrw_delay = ATH79_SPI_RRW_DELAY_FACTOR / rate;
+        dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
+                sp->rrw_delay);
+
         ret = spi_bitbang_start(&sp->bitbang);
         if (ret)
-                goto err_unmap;
+                goto err_clk_disable;
 
         return 0;
 
+err_clk_disable:
+        clk_disable(sp->clk);
+err_clk_put:
+        clk_put(sp->clk);
 err_unmap:
         iounmap(sp->base);
 err_put_master:
@@ -256,6 +296,8 @@ static int ath79_spi_remove(struct platform_device *pdev)
         struct ath79_spi *sp = platform_get_drvdata(pdev);
 
         spi_bitbang_stop(&sp->bitbang);
+        clk_disable(sp->clk);
+        clk_put(sp->clk);
         iounmap(sp->base);
         platform_set_drvdata(pdev, NULL);
         spi_master_put(sp->bitbang.master);