From d6786fefe816ba60c794f8a41a73b0dd3a4df097 Mon Sep 17 00:00:00 2001 From: Guodong Xu Date: Fri, 12 Aug 2016 16:51:26 +0800 Subject: [PATCH] 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 Signed-off-by: Xinwei Kong Signed-off-by: Zhangfei Gao Reviewed-by: Shawn Lin Signed-off-by: Jaehoon Chung Signed-off-by: Ulf Hansson --- 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 1a1e1e1ac7c1..e7eef75a65ef 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -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); } diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h index 83b0edfce471..f5af2bd35e7f 100644 --- a/include/linux/mmc/dw_mmc.h +++ b/include/linux/mmc/dw_mmc.h @@ -17,6 +17,7 @@ #include #include #include +#include #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; }; -- 2.20.1