1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * (C) Copyright 2018 Cisco Systems, Inc. 4 * 5 * Author: Thomas Fitzsimmons <fitzsim@fitzsim.org> 6 */ 7 8 #include <common.h> 9 #include <mach/sdhci.h> 10 #include <malloc.h> 11 #include <sdhci.h> 12 13 /* 14 * The BCMSTB SDHCI has a quirk in that its actual maximum frequency 15 * capability is 100 MHz. The divisor that is eventually written to 16 * SDHCI_CLOCK_CONTROL is calculated based on what the MMC device 17 * reports, and relative to this maximum frequency. 18 * 19 * This define used to be set to 52000000 (52 MHz), the desired 20 * maximum frequency, but that would result in the communication 21 * actually running at 100 MHz (seemingly without issue), which is 22 * out-of-spec. 23 * 24 * Now, by setting this to 0 (auto-detect), 100 MHz will be read from 25 * the capabilities register, and the resulting divisor will be 26 * doubled, meaning that the clock control register will be set to the 27 * in-spec 52 MHz value. 28 */ 29 #define BCMSTB_SDHCI_MAXIMUM_CLOCK_FREQUENCY 0 30 /* 31 * When the minimum clock frequency is set to 0 (auto-detect), U-Boot 32 * sets it to 100 MHz divided by SDHCI_MAX_DIV_SPEC_300, or 48,875 Hz, 33 * which results in the controller timing out when trying to 34 * communicate with the MMC device. Hard-code this value to 400000 35 * (400 kHz) to prevent this. 36 */ 37 #define BCMSTB_SDHCI_MINIMUM_CLOCK_FREQUENCY 400000 38 39 static char *BCMSTB_SDHCI_NAME = "bcmstb-sdhci"; 40 41 /* 42 * This driver has only been tested with eMMC devices; SD devices may 43 * not work. 44 */ 45 int bcmstb_sdhci_init(phys_addr_t regbase) 46 { 47 struct sdhci_host *host = NULL; 48 49 host = (struct sdhci_host *)malloc(sizeof(struct sdhci_host)); 50 if (!host) { 51 printf("%s: Failed to allocate memory\n", __func__); 52 return 1; 53 } 54 memset(host, 0, sizeof(*host)); 55 56 host->name = BCMSTB_SDHCI_NAME; 57 host->ioaddr = (void *)regbase; 58 host->quirks = 0; 59 60 host->cfg.part_type = PART_TYPE_DOS; 61 62 host->version = sdhci_readw(host, SDHCI_HOST_VERSION); 63 64 return add_sdhci(host, 65 BCMSTB_SDHCI_MAXIMUM_CLOCK_FREQUENCY, 66 BCMSTB_SDHCI_MINIMUM_CLOCK_FREQUENCY); 67 } 68