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@xxxxxxxxxxxxx>
---
drivers/mmc/host/sdhci-esdhc-imx.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 8f0bc6dca2b0402fd2a0695903cf261a5b4e19dc..a830d9a9490408d3148b927bf1acc719a13e8975 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -33,6 +33,8 @@
#define ESDHC_SYS_CTRL_DTOCV_MASK 0x0f
#define ESDHC_CTRL_D3CD 0x08
#define ESDHC_BURST_LEN_EN_INCR (1 << 27)
+#define ESDHC_SYS_CTRL 0x2c
+#define ESDHC_SYS_CTRL_IPP_RST_N BIT(23)
/* VENDOR SPEC register */
#define ESDHC_VENDOR_SPEC 0xc0
#define ESDHC_VENDOR_SPEC_SDIO_QUIRK (1 << 1)
@@ -1402,6 +1404,17 @@ 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_SYS_CTRL);
+ /* 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_SYS_CTRL);
+ /* 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,
@@ -1420,6 +1433,7 @@ 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 = {
--
2.43.0
