* [PATCH v5 2/2] mmc: dw_mmc: add reset support to dwmmc host controller
2016-08-12 8:51 ` [PATCH v5 0/2] mmc: dw_mmc: host controller reset support Guodong Xu
[not found] ` <1470991886-22412-1-git-send-email-guodong.xu-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
@ 2016-08-12 8:51 ` Guodong Xu
2016-08-12 9:19 ` [PATCH v5 0/2] mmc: dw_mmc: host controller reset support Jaehoon Chung
2 siblings, 0 replies; 4+ messages in thread
From: Guodong Xu @ 2016-08-12 8:51 UTC (permalink / raw)
To: heiko, shawn.lin, jh80.chung, robh+dt, mark.rutland, ulf.hansson,
guodong.xu
Cc: devicetree, linux-kernel, linux-arm-kernel, linux-mmc,
Xinwei Kong, Zhangfei Gao
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>
---
drivers/mmc/host/dw_mmc.c | 23 ++++++++++++++++++++++-
include/linux/mmc/dw_mmc.h | 2 ++
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 1b719a6..4dff0ee 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2872,6 +2872,13 @@ 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);
@@ -2943,7 +2950,9 @@ 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;
}
@@ -2997,6 +3006,12 @@ 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);
@@ -3146,6 +3161,9 @@ 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);
@@ -3176,6 +3194,9 @@ 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);
}
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 @@ 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;
};
--
1.9.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v5 0/2] mmc: dw_mmc: host controller reset support
2016-08-12 8:51 ` [PATCH v5 0/2] mmc: dw_mmc: host controller reset support Guodong Xu
[not found] ` <1470991886-22412-1-git-send-email-guodong.xu-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2016-08-12 8:51 ` [PATCH v5 2/2] mmc: dw_mmc: add reset support to dwmmc host controller Guodong Xu
@ 2016-08-12 9:19 ` Jaehoon Chung
2 siblings, 0 replies; 4+ messages in thread
From: Jaehoon Chung @ 2016-08-12 9:19 UTC (permalink / raw)
To: Guodong Xu, heiko, shawn.lin, robh+dt, mark.rutland, ulf.hansson
Cc: devicetree, linux-kernel, linux-arm-kernel, linux-mmc
Hi Guodong,
On 08/12/2016 05:51 PM, Guodong Xu wrote:
> mmc host controller registers may in abnormal state if mmc is used in
> bootloader, eg. to load kernel from eMMC. Some controllers cann't
> clear their registers when clk is set. They use dedicated reset
> logics to do this.
>
> In this patch, a 'resets' property is added into dw_mmc dts
> node. When driver does parse_dt and probe, it calls reset API to
> triiger 'reset' of dwmmc host controller. When probe error or
> remove, it calls reset API to assert it.
>
> Chip vendor's actual reset logics is implemented in reset driver, not
> in dw_mmc code.
>
> Please also refer to Documentation/devicetree/bindings/reset/reset.txt
>
> Changelog:
> v5:
> * rebase onto https://github.com/jh80chung/dw-mmc
> v4:
> * add reset_control_assert() and usleep() before calling _deassert().
>
> Guodong Xu (2):
> Documentation: synopsys-dw-mshc: add binding for resets
> mmc: dw_mmc: add reset support to dwmmc host controller
Applied on my dw-mmc tree. Thanks!
Best Regards,
Jaehoon Chung
>
> .../devicetree/bindings/mmc/synopsys-dw-mshc.txt | 4 ++++
> drivers/mmc/host/dw_mmc.c | 23 +++++++++++++++++++++-
> include/linux/mmc/dw_mmc.h | 2 ++
> 3 files changed, 28 insertions(+), 1 deletion(-)
>
^ permalink raw reply [flat|nested] 4+ messages in thread