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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>
This commit is contained in:
Guodong Xu 2016-08-12 16:51:26 +08:00 committed by Ulf Hansson
parent fdc22b6b1f
commit d6786fefe8
2 changed files with 24 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/mmc/host/dw_mmc.c
View File

@ -2876,6 +2876,13 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
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 @@ int dw_mci_probe(struct dw_mci *host)
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 @@ int dw_mci_probe(struct dw_mci *host)
}
}
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 @@ err_dmaunmap:
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 @@ void dw_mci_remove(struct dw_mci *host)
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);
}

2
include/linux/mmc/dw_mmc.h
View File

@ -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 @@ struct dw_mci_board {
/* 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;
};