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| author | Josua Mayer <josua@solid-run.com> | 2024-11-01 12:42:25 +0100 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2024-11-04 12:16:30 +0100 |
| commit | 8ba9d45a33c849c50053ba7b6ef4706bbb3ff709 (patch) | |
| tree | 46feddc95406bfbac63a6f4f3b7d57e467802eb2 /drivers/mmc | |
| parent | 53857ced9f23c8720d148748fff434386780afab (diff) | |
| download | lwn-8ba9d45a33c849c50053ba7b6ef4706bbb3ff709.tar.gz lwn-8ba9d45a33c849c50053ba7b6ef4706bbb3ff709.zip | |
mmc: sdhci-esdhc-imx: Implement emmc hardware reset
NXP ESDHC supports control of native emmc reset signal when pinmux is
set accordingly, using uSDHCx_SYS_CTRL register IPP_RST_N bit.
Documentation is available in NXP i.MX6Q Reference Manual.
Implement the hw_reset function in sdhci_ops asserting reset for at
least 1us and waiting at least 200us after deassertion.
Lower bounds are based on:
JEDEC Standard No. 84-B51, 6.15.10 H/W Reset Operation, page 159.
Upper bounds are chosen allowing flexibility to the scheduler.
Tested on SolidRun i.MX8DXL SoM with a scope, and confirmed that eMMC is
still accessible after boot:
- eMMC extcsd has RST_N_FUNCTION=0x01
- sdhc node has cap-mmc-hw-reset
- pinmux set for EMMC0_RESET_B
- Linux v5.15
Signed-off-by: Josua Mayer <josua@solid-run.com>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Message-ID: <20241101-imx-emmc-reset-v3-1-184965eed476@solid-run.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/host/sdhci-esdhc-imx.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c index c7582ad45123..8f0a3d933ea9 100644 --- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c @@ -31,6 +31,7 @@ #include "cqhci.h" #define ESDHC_SYS_CTRL_DTOCV_MASK 0x0f +#define ESDHC_SYS_CTRL_IPP_RST_N BIT(23) #define ESDHC_CTRL_D3CD 0x08 #define ESDHC_BURST_LEN_EN_INCR (1 << 27) /* VENDOR SPEC register */ @@ -1407,6 +1408,17 @@ static u32 esdhc_cqhci_irq(struct sdhci_host *host, u32 intmask) return 0; } +static void esdhc_hw_reset(struct sdhci_host *host) +{ + esdhc_clrset_le(host, ESDHC_SYS_CTRL_IPP_RST_N, 0, ESDHC_SYSTEM_CONTROL); + /* eMMC spec requires minimum 1us, here delay between 1-10us */ + usleep_range(1, 10); + esdhc_clrset_le(host, ESDHC_SYS_CTRL_IPP_RST_N, + ESDHC_SYS_CTRL_IPP_RST_N, ESDHC_SYSTEM_CONTROL); + /* eMMC spec requires minimum 200us, here delay between 200-300us */ + usleep_range(200, 300); +} + static struct sdhci_ops sdhci_esdhc_ops = { .read_l = esdhc_readl_le, .read_w = esdhc_readw_le, @@ -1425,6 +1437,7 @@ static struct sdhci_ops sdhci_esdhc_ops = { .reset = esdhc_reset, .irq = esdhc_cqhci_irq, .dump_vendor_regs = esdhc_dump_debug_regs, + .hw_reset = esdhc_hw_reset, }; static const struct sdhci_pltfm_data sdhci_esdhc_imx_pdata = { |