[MMC] sdhci: proper timeout handling

Use the give timeout clock and calculate a proper timeout instead of using the
maximum at all times.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 44 insertions, 3 deletions

diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 77b7db27b555..877226e2ffae 100644
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -128,9 +128,6 @@ static void sdhci_init(struct sdhci_host *host)
 
         writel(intmask, host->ioaddr + SDHCI_INT_ENABLE);
         writel(intmask, host->ioaddr + SDHCI_SIGNAL_ENABLE);
-
-        /* This is unknown magic. */
-        writeb(0xE, host->ioaddr + SDHCI_TIMEOUT_CONTROL);
 }
 
 static void sdhci_activate_led(struct sdhci_host *host)
@@ -274,6 +271,8 @@ static void sdhci_transfer_pio(struct sdhci_host *host)
 static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
 {
         u16 mode;
+        u8 count;
+        unsigned target_timeout, current_timeout;
 
         WARN_ON(host->data);
 
@@ -287,6 +286,37 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
         DBG("tsac %d ms nsac %d clk\n",
                 data->timeout_ns / 1000000, data->timeout_clks);
 
+        /* timeout in us */
+        target_timeout = data->timeout_ns / 1000 +
+                data->timeout_clks / host->clock;
+
+        /*
+         * Figure out needed cycles.
+         * We do this in steps in order to fit inside a 32 bit int.
+         * The first step is the minimum timeout, which will have a
+         * minimum resolution of 6 bits:
+         * (1) 2^13*1000 > 2^22,
+         * (2) host->timeout_clk < 2^16
+         *     =>
+         *     (1) / (2) > 2^6
+         */
+        count = 0;
+        current_timeout = (1 << 13) * 1000 / host->timeout_clk;
+        while (current_timeout < target_timeout) {
+                count++;
+                current_timeout <<= 1;
+                if (count >= 0xF)
+                        break;
+        }
+
+        if (count >= 0xF) {
+                printk(KERN_WARNING "%s: Too large timeout requested!\n",
+                        mmc_hostname(host->mmc));
+                count = 0xE;
+        }
+
+        writeb(count, host->ioaddr + SDHCI_TIMEOUT_CONTROL);
+
         mode = SDHCI_TRNS_BLK_CNT_EN;
         if (data->blocks > 1)
                 mode |= SDHCI_TRNS_MULTI;
@@ -1096,6 +1126,17 @@ static int __devinit sdhci_probe_slot(struct pci_dev *pdev, int slot)
         }
         host->max_clk *= 1000000;
 
+        host->timeout_clk =
+                (caps & SDHCI_TIMEOUT_CLK_MASK) >> SDHCI_TIMEOUT_CLK_SHIFT;
+        if (host->timeout_clk == 0) {
+                printk(KERN_ERR "%s: Hardware doesn't specify timeout clock "
+                        "frequency.\n", host->slot_descr);
+                ret = -ENODEV;
+                goto unmap;
+        }
+        if (caps & SDHCI_TIMEOUT_CLK_UNIT)
+                host->timeout_clk *= 1000;
+
         /*
          * Set host parameters.
          */