1 files changed, 67 insertions, 0 deletions
diff --git a/drivers/mmc/bcmstb_sdhci.c b/drivers/mmc/bcmstb_sdhci.c
new file mode 100644
index 0000000000..443ae8d481
--- /dev/null
+++ b/drivers/mmc/bcmstb_sdhci.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2018  Cisco Systems, Inc.
+ *
+ * Author: Thomas Fitzsimmons <fitzsim@fitzsim.org>
+ */
+
+#include <common.h>
+#include <mach/sdhci.h>
+#include <malloc.h>
+#include <sdhci.h>
+
+/*
+ * The BCMSTB SDHCI has a quirk in that its actual maximum frequency
+ * capability is 100 MHz.  The divisor that is eventually written to
+ * SDHCI_CLOCK_CONTROL is calculated based on what the MMC device
+ * reports, and relative to this maximum frequency.
+ *
+ * This define used to be set to 52000000 (52 MHz), the desired
+ * maximum frequency, but that would result in the communication
+ * actually running at 100 MHz (seemingly without issue), which is
+ * out-of-spec.
+ *
+ * Now, by setting this to 0 (auto-detect), 100 MHz will be read from
+ * the capabilities register, and the resulting divisor will be
+ * doubled, meaning that the clock control register will be set to the
+ * in-spec 52 MHz value.
+ */
+#define BCMSTB_SDHCI_MAXIMUM_CLOCK_FREQUENCY	0
+/*
+ * When the minimum clock frequency is set to 0 (auto-detect), U-Boot
+ * sets it to 100 MHz divided by SDHCI_MAX_DIV_SPEC_300, or 48,875 Hz,
+ * which results in the controller timing out when trying to
+ * communicate with the MMC device.  Hard-code this value to 400000
+ * (400 kHz) to prevent this.
+ */
+#define BCMSTB_SDHCI_MINIMUM_CLOCK_FREQUENCY	400000
+
+static char *BCMSTB_SDHCI_NAME = "bcmstb-sdhci";
+
+/*
+ * This driver has only been tested with eMMC devices; SD devices may
+ * not work.
+ */
+int bcmstb_sdhci_init(phys_addr_t regbase)
+{
+	struct sdhci_host *host = NULL;
+
+	host = (struct sdhci_host *)malloc(sizeof(struct sdhci_host));
+	if (!host) {
+		printf("%s: Failed to allocate memory\n", __func__);
+		return 1;
+	}
+	memset(host, 0, sizeof(*host));
+
+	host->name = BCMSTB_SDHCI_NAME;
+	host->ioaddr = (void *)regbase;
+	host->quirks = 0;
+
+	host->cfg.part_type = PART_TYPE_DOS;
+
+	host->version = sdhci_readw(host, SDHCI_HOST_VERSION);
+
+	return add_sdhci(host,
+			 BCMSTB_SDHCI_MAXIMUM_CLOCK_FREQUENCY,
+			 BCMSTB_SDHCI_MINIMUM_CLOCK_FREQUENCY);
+}