[PATCH 4/5] omap mmc: force MMC module reset on boot

Tony Lindgren
2008-12-07T21:50:34Z

From: Kevin Hilman <khilman@deeprootsystems.com>

The bootloader may leave the MMC in a state which prevents hitting
retention. Even when MMC is not compiled in, each MMC module needs to
be forced into reset.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
arch/arm/mach-omap2/devices.c | 85 +++++++++++++++++++++++++++++++++++++++++
1 files changed, 85 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-omap2/devices.c b/arch/arm/mach-omap2/devices.c
index 6e03272..9d7216f 100644
--- a/arch/arm/mach-omap2/devices.c
+++ b/arch/arm/mach-omap2/devices.c
@@ -14,6 +14,7 @@
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/io.h>
+#include <linux/clk.h>

#include <mach/hardware.h>
#include <asm/mach-types.h>
@@ -299,6 +300,89 @@ static inline void omap_init_sha1_md5(void) { }

/*-------------------------------------------------------------------------*/

+#ifdef CONFIG_ARCH_OMAP3
+
+#define MMCHS_SYSCONFIG 0x0010
+#define MMCHS_SYSCONFIG_SWRESET (1 << 1)
+#define MMCHS_SYSSTATUS 0x0014
+#define MMCHS_SYSSTATUS_RESETDONE (1 << 0)
+
+static struct platform_device dummy_pdev = {
+ .dev = {
+ .bus = &platform_bus_type,
+ },
+};
+
+/**
+ * omap_hsmmc_reset() - Full reset of each HS-MMC controller
+ *
+ * Ensure that each MMC controller is fully reset. Controllers
+ * left in an unknown state (by bootloader) may prevent retention
+ * or OFF-mode. This is especially important in cases where the
+ * MMC driver is not enabled, _or_ built as a module.
+ *
+ * In order for reset to work, interface, functional and debounce
+ * clocks must be enabled. The debounce clock comes from func_32k_clk
+ * and is not under SW control, so we only enable i- and f-clocks.
+ **/
+static void __init omap_hsmmc_reset(void)
+{
+ u32 i, nr_controllers = cpu_is_omap34xx() ? OMAP34XX_NR_MMC :
+ OMAP24XX_NR_MMC;
+
+ for (i = 0; i < nr_controllers; i++) {
+ u32 v, base = 0;
+ struct clk *iclk, *fclk;
+ struct device *dev = &dummy_pdev.dev;
+
+ switch (i) {
+ case 0:
+ base = OMAP2_MMC1_BASE;
+ break;
+ case 1:
+ base = OMAP2_MMC2_BASE;
+ break;
+ case 2:
+ base = OMAP3_MMC3_BASE;
+ break;
+ }
+
+ dummy_pdev.id = i;
+ iclk = clk_get(dev, "mmchs_ick");
+ if (iclk && clk_enable(iclk))
+ iclk = NULL;
+
+ fclk = clk_get(dev, "mmchs_fck");
+ if (fclk && clk_enable(fclk))
+ fclk = NULL;
+
+ if (!iclk || !fclk) {
+ printk(KERN_WARNING
+ "%s: Unable to enable clocks for MMC%d, "
+ "cannot reset.\n", __func__, i);
+ break;
+ }
+
+ omap_writel(MMCHS_SYSCONFIG_SWRESET, base + MMCHS_SYSCONFIG);
+ v = omap_readl(base + MMCHS_SYSSTATUS);
+ while (!(omap_readl(base + MMCHS_SYSSTATUS) &
+ MMCHS_SYSSTATUS_RESETDONE))
+ cpu_relax();
+
+ if (fclk) {
+ clk_disable(fclk);
+ clk_put(fclk);
+ }
+ if (iclk) {
+ clk_disable(iclk);
+ clk_put(iclk);
+ }
+ }
+}
+#else
+static inline void omap_hsmmc_reset(void) {}
+#endif
+
#if defined(CONFIG_MMC_OMAP) || defined(CONFIG_MMC_OMAP_MODULE) || \
defined(CONFIG_MMC_OMAP_HS) || defined(CONFIG_MMC_OMAP_HS_MODULE)

@@ -418,6 +502,7 @@ static int __init omap2_init_devices(void)
/* please keep these calls, and their implementations above,
* in alphabetical order so they're easier to sort through.
*/
+ omap_hsmmc_reset();
omap_init_mbox();
omap_init_mcspi();
omap_hdq_init();