pata: imx: add support of setting timings for PIO modes

The controller is capable to operate in up to PIO4 mode, however
before the change the driver relies on timing settings done by
a bootloader for PIO0 mode only. The change adds more flexibility
in PIO mode selection at runtime and makes the driver to work even if
bootloader does not preset ATA timings.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 46 insertions, 1 deletions

diff --git a/drivers/ata/pata_imx.c b/drivers/ata/pata_imx.c
index 00df18b07fa6..8f13c9f27c8c 100644
--- a/drivers/ata/pata_imx.c
+++ b/drivers/ata/pata_imx.c
@@ -11,7 +11,6 @@
  *
  * TODO:
  * - dmaengine support
- * - check if timing stuff needed
  */
 
 #include <linux/ata.h>
@@ -22,6 +21,16 @@
 
 #define DRV_NAME "pata_imx"
 
+#define PATA_IMX_ATA_TIME_OFF           0x00
+#define PATA_IMX_ATA_TIME_ON            0x01
+#define PATA_IMX_ATA_TIME_1             0x02
+#define PATA_IMX_ATA_TIME_2W            0x03
+#define PATA_IMX_ATA_TIME_2R            0x04
+#define PATA_IMX_ATA_TIME_AX            0x05
+#define PATA_IMX_ATA_TIME_PIO_RDX       0x06
+#define PATA_IMX_ATA_TIME_4             0x07
+#define PATA_IMX_ATA_TIME_9             0x08
+
 #define PATA_IMX_ATA_CONTROL            0x24
 #define PATA_IMX_ATA_CTRL_FIFO_RST_B    (1<<7)
 #define PATA_IMX_ATA_CTRL_ATA_RST_B     (1<<6)
@@ -31,6 +40,10 @@
 #define PATA_IMX_DRIVE_DATA             0xA0
 #define PATA_IMX_DRIVE_CONTROL          0xD8
 
+static u32 pio_t4[] = { 30,  20,  15,  10,  10 };
+static u32 pio_t9[] = { 20,  15,  10,  10,  10 };
+static u32 pio_tA[] = { 35,  35,  35,  35,  35 };
+
 struct pata_imx_priv {
         struct clk *clk;
         /* timings/interrupt/control regs */
@@ -38,11 +51,43 @@ struct pata_imx_priv {
         u32 ata_ctl;
 };
 
+static void pata_imx_set_timing(struct ata_device *adev,
+                                struct pata_imx_priv *priv)
+{
+        struct ata_timing timing;
+        unsigned long clkrate;
+        u32 T, mode;
+
+        clkrate = clk_get_rate(priv->clk);
+
+        if (adev->pio_mode < XFER_PIO_0 || adev->pio_mode > XFER_PIO_4 ||
+            !clkrate)
+                return;
+
+        T = 1000000000 / clkrate;
+        ata_timing_compute(adev, adev->pio_mode, &timing, T * 1000, 0);
+
+        mode = adev->pio_mode - XFER_PIO_0;
+
+        writeb(3, priv->host_regs + PATA_IMX_ATA_TIME_OFF);
+        writeb(3, priv->host_regs + PATA_IMX_ATA_TIME_ON);
+        writeb(timing.setup, priv->host_regs + PATA_IMX_ATA_TIME_1);
+        writeb(timing.act8b, priv->host_regs + PATA_IMX_ATA_TIME_2W);
+        writeb(timing.act8b, priv->host_regs + PATA_IMX_ATA_TIME_2R);
+        writeb(1, priv->host_regs + PATA_IMX_ATA_TIME_PIO_RDX);
+
+        writeb(pio_t4[mode] / T + 1, priv->host_regs + PATA_IMX_ATA_TIME_4);
+        writeb(pio_t9[mode] / T + 1, priv->host_regs + PATA_IMX_ATA_TIME_9);
+        writeb(pio_tA[mode] / T + 1, priv->host_regs + PATA_IMX_ATA_TIME_AX);
+}
+
 static void pata_imx_set_piomode(struct ata_port *ap, struct ata_device *adev)
 {
         struct pata_imx_priv *priv = ap->host->private_data;
         u32 val;
 
+        pata_imx_set_timing(adev, priv);
+
         val = __raw_readl(priv->host_regs + PATA_IMX_ATA_CONTROL);
         if (ata_pio_need_iordy(adev))
                 val |= PATA_IMX_ATA_CTRL_IORDY_EN;