mmc: dw_mmc: add reset support to dwmmc host controller
Dwmmc host controller may in unknown state when entering kernel boot. One
example is when booting from eMMC, bootloader need initialize MMC host
controller into some state so it can read. In order to make sure MMC host
controller in a clean initial state, this reset support is added.
With this patch, a 'resets' property can be added into dw_mmc device
tree node. The hardware logic is: dwmmc host controller IP receives a reset
signal from a 'reset provider' (eg. power management unit). The 'resets'
property points to this reset signal. So, during dwmmc driver probe,
it can use this signal to reset itself.
Refer to [1] for more information.
[1] Documentation/devicetree/bindings/reset/reset.txt
Signed-off-by: Guodong Xu <guodong.xu@linaro.org>
Signed-off-by: Xinwei Kong <kong.kongxinwei@hisilicon.com>
Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 1a1e1e1..e7eef75 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2876,6 +2876,13 @@
if (!pdata)
return ERR_PTR(-ENOMEM);
+ /* find reset controller when exist */
+ pdata->rstc = devm_reset_control_get_optional(dev, NULL);
+ if (IS_ERR(pdata->rstc)) {
+ if (PTR_ERR(pdata->rstc) == -EPROBE_DEFER)
+ return ERR_PTR(-EPROBE_DEFER);
+ }
+
/* find out number of slots supported */
of_property_read_u32(np, "num-slots", &pdata->num_slots);
@@ -2947,7 +2954,9 @@
if (!host->pdata) {
host->pdata = dw_mci_parse_dt(host);
- if (IS_ERR(host->pdata)) {
+ if (PTR_ERR(host->pdata) == -EPROBE_DEFER) {
+ return -EPROBE_DEFER;
+ } else if (IS_ERR(host->pdata)) {
dev_err(host->dev, "platform data not available\n");
return -EINVAL;
}
@@ -3001,6 +3010,12 @@
}
}
+ if (!IS_ERR(host->pdata->rstc)) {
+ reset_control_assert(host->pdata->rstc);
+ usleep_range(10, 50);
+ reset_control_deassert(host->pdata->rstc);
+ }
+
setup_timer(&host->cmd11_timer,
dw_mci_cmd11_timer, (unsigned long)host);
@@ -3150,6 +3165,9 @@
if (host->use_dma && host->dma_ops->exit)
host->dma_ops->exit(host);
+ if (!IS_ERR(host->pdata->rstc))
+ reset_control_assert(host->pdata->rstc);
+
err_clk_ciu:
clk_disable_unprepare(host->ciu_clk);
@@ -3180,6 +3198,9 @@
if (host->use_dma && host->dma_ops->exit)
host->dma_ops->exit(host);
+ if (!IS_ERR(host->pdata->rstc))
+ reset_control_assert(host->pdata->rstc);
+
clk_disable_unprepare(host->ciu_clk);
clk_disable_unprepare(host->biu_clk);
}
diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
index 83b0edfc..f5af2bd 100644
--- a/include/linux/mmc/dw_mmc.h
+++ b/include/linux/mmc/dw_mmc.h
@@ -17,6 +17,7 @@
#include <linux/scatterlist.h>
#include <linux/mmc/core.h>
#include <linux/dmaengine.h>
+#include <linux/reset.h>
#define MAX_MCI_SLOTS 2
@@ -259,6 +260,7 @@
/* delay in mS before detecting cards after interrupt */
u32 detect_delay_ms;
+ struct reset_control *rstc;
struct dw_mci_dma_ops *dma_ops;
struct dma_pdata *data;
};