[PATCH 1/4 v2] mmc: mn57xx: only access registers above 0xff, if available

[Guennadi Liakhovetski <g.liakhovetski@xxxxxx>]

Not all mn57xx / tmio implementations have registers above oxff.
Accessing them on thise platforms is dangerous. In some cases it leads
to address wrapping to addresses below 0x100, which corrupts random
unrelated registers.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
---

v2:

1. rebase on top of driver split
2. use Paul's idea to check the resource size
3. avoid even a shortest regression between two patches in a series - 
   first add a check, then fix users, and only then remove the 
   work-around.

 drivers/mmc/host/tmio_mmc_pio.c |   25 +++++++++++++++++++------
 1 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
index a7406e3..28e14c7 100644
--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -209,6 +209,7 @@ static void tmio_mmc_set_clock(struct tmio_mmc_host *host, int new_clock)
 static void tmio_mmc_clk_stop(struct tmio_mmc_host *host)
 {
 	struct tmio_mmc_data *pdata = host->pdata;
+	struct resource *res = platform_get_resource(host->pdev, IORESOURCE_MEM, 0);
 
 	/*
 	 * Testing on sh-mobile showed that SDIO IRQs are unmasked when
@@ -218,8 +219,11 @@ static void tmio_mmc_clk_stop(struct tmio_mmc_host *host)
 	 */
 	if (pdata->flags & TMIO_MMC_SDIO_IRQ)
 		disable_irq(host->irq);
-	sd_ctrl_write16(host, CTL_CLK_AND_WAIT_CTL, 0x0000);
-	msleep(10);
+	/* implicit BUG_ON(!res) */
+	if (resource_size(res) > 0x100) {
+		sd_ctrl_write16(host, CTL_CLK_AND_WAIT_CTL, 0x0000);
+		msleep(10);
+	}
 	if (pdata->flags & TMIO_MMC_SDIO_IRQ) {
 		tmio_mmc_enable_sdio_irq(host->mmc, host->sdio_irq_enabled);
 		enable_irq(host->irq);
@@ -232,6 +236,7 @@ static void tmio_mmc_clk_stop(struct tmio_mmc_host *host)
 static void tmio_mmc_clk_start(struct tmio_mmc_host *host)
 {
 	struct tmio_mmc_data *pdata = host->pdata;
+	struct resource *res = platform_get_resource(host->pdev, IORESOURCE_MEM, 0);
 
 	sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, 0x0100 |
 		sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));
@@ -239,8 +244,11 @@ static void tmio_mmc_clk_start(struct tmio_mmc_host *host)
 	/* see comment in tmio_mmc_clk_stop above */
 	if (pdata->flags & TMIO_MMC_SDIO_IRQ)
 		disable_irq(host->irq);
-	sd_ctrl_write16(host, CTL_CLK_AND_WAIT_CTL, 0x0100);
-	msleep(10);
+	/* implicit BUG_ON(!res) */
+	if (resource_size(res) > 0x100) {
+		sd_ctrl_write16(host, CTL_CLK_AND_WAIT_CTL, 0x0100);
+		msleep(10);
+	}
 	if (pdata->flags & TMIO_MMC_SDIO_IRQ) {
 		tmio_mmc_enable_sdio_irq(host->mmc, host->sdio_irq_enabled);
 		enable_irq(host->irq);
@@ -249,12 +257,17 @@ static void tmio_mmc_clk_start(struct tmio_mmc_host *host)
 
 static void tmio_mmc_reset(struct tmio_mmc_host *host)
 {
+	struct resource *res = platform_get_resource(host->pdev, IORESOURCE_MEM, 0);
+
 	/* FIXME - should we set stop clock reg here */
 	sd_ctrl_write16(host, CTL_RESET_SD, 0x0000);
-	sd_ctrl_write16(host, CTL_RESET_SDIO, 0x0000);
+	/* implicit BUG_ON(!res) */
+	if (resource_size(res) > 0x100)
+		sd_ctrl_write16(host, CTL_RESET_SDIO, 0x0000);
 	msleep(10);
 	sd_ctrl_write16(host, CTL_RESET_SD, 0x0001);
-	sd_ctrl_write16(host, CTL_RESET_SDIO, 0x0001);
+	if (resource_size(res) > 0x100)
+		sd_ctrl_write16(host, CTL_RESET_SDIO, 0x0001);
 	msleep(10);
 }
 
-- 
1.7.2.3

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