diff options
Diffstat (limited to 'drivers/mmc/bcm2835_sdhci.c')
| -rw-r--r-- | drivers/mmc/bcm2835_sdhci.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/drivers/mmc/bcm2835_sdhci.c b/drivers/mmc/bcm2835_sdhci.c new file mode 100644 index 000000000..b0afc3c9c --- /dev/null +++ b/drivers/mmc/bcm2835_sdhci.c @@ -0,0 +1,189 @@ +/* + * This code was extracted from: + * git://github.com/gonzoua/u-boot-pi.git master + * and hence presumably (C) 2012 Oleksandr Tymoshenko + * + * Tweaks for U-Boot upstreaming + * (C) 2012 Stephen Warren + * + * Portions (e.g. read/write macros, concepts for back-to-back register write + * timing workarounds) obviously extracted from the Linux kernel at: + * https://github.com/raspberrypi/linux.git rpi-3.6.y + * + * The Linux kernel code has the following (c) and license, which is hence + * propagated to Oleksandr's tree and here: + * + * Support for SDHCI device on 2835 + * Based on sdhci-bcm2708.c (c) 2010 Broadcom + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +/* Supports: + * SDHCI platform device - Arasan SD controller in BCM2708 + * + * Inspired by sdhci-pci.c, by Pierre Ossman + */ + +#include <common.h> +#include <malloc.h> +#include <sdhci.h> + +/* 400KHz is max freq for card ID etc. Use that as min */ +#define MIN_FREQ 400000 + +struct bcm2835_sdhci_host { + struct sdhci_host host; + uint twoticks_delay; + ulong last_write; +}; + +static inline struct bcm2835_sdhci_host *to_bcm(struct sdhci_host *host) +{ + return (struct bcm2835_sdhci_host *)host; +} + +static inline void bcm2835_sdhci_raw_writel(struct sdhci_host *host, u32 val, + int reg) +{ + struct bcm2835_sdhci_host *bcm_host = to_bcm(host); + + /* + * The Arasan has a bugette whereby it may lose the content of + * successive writes to registers that are within two SD-card clock + * cycles of each other (a clock domain crossing problem). + * It seems, however, that the data register does not have this problem. + * (Which is just as well - otherwise we'd have to nobble the DMA engine + * too) + */ + while (get_timer(bcm_host->last_write) < bcm_host->twoticks_delay) + ; + + writel(val, host->ioaddr + reg); + bcm_host->last_write = get_timer(0); +} + +static inline u32 bcm2835_sdhci_raw_readl(struct sdhci_host *host, int reg) +{ + return readl(host->ioaddr + reg); +} + +static void bcm2835_sdhci_writel(struct sdhci_host *host, u32 val, int reg) +{ + bcm2835_sdhci_raw_writel(host, val, reg); +} + +static void bcm2835_sdhci_writew(struct sdhci_host *host, u16 val, int reg) +{ + static u32 shadow; + u32 oldval = (reg == SDHCI_COMMAND) ? shadow : + bcm2835_sdhci_raw_readl(host, reg & ~3); + u32 word_num = (reg >> 1) & 1; + u32 word_shift = word_num * 16; + u32 mask = 0xffff << word_shift; + u32 newval = (oldval & ~mask) | (val << word_shift); + + if (reg == SDHCI_TRANSFER_MODE) + shadow = newval; + else + bcm2835_sdhci_raw_writel(host, newval, reg & ~3); +} + +static void bcm2835_sdhci_writeb(struct sdhci_host *host, u8 val, int reg) +{ + u32 oldval = bcm2835_sdhci_raw_readl(host, reg & ~3); + u32 byte_num = reg & 3; + u32 byte_shift = byte_num * 8; + u32 mask = 0xff << byte_shift; + u32 newval = (oldval & ~mask) | (val << byte_shift); + + bcm2835_sdhci_raw_writel(host, newval, reg & ~3); +} + +static u32 bcm2835_sdhci_readl(struct sdhci_host *host, int reg) +{ + u32 val = bcm2835_sdhci_raw_readl(host, reg); + + return val; +} + +static u16 bcm2835_sdhci_readw(struct sdhci_host *host, int reg) +{ + u32 val = bcm2835_sdhci_raw_readl(host, (reg & ~3)); + u32 word_num = (reg >> 1) & 1; + u32 word_shift = word_num * 16; + u32 word = (val >> word_shift) & 0xffff; + + return word; +} + +static u8 bcm2835_sdhci_readb(struct sdhci_host *host, int reg) +{ + u32 val = bcm2835_sdhci_raw_readl(host, (reg & ~3)); + u32 byte_num = reg & 3; + u32 byte_shift = byte_num * 8; + u32 byte = (val >> byte_shift) & 0xff; + + return byte; +} + +static const struct sdhci_ops bcm2835_ops = { + .write_l = bcm2835_sdhci_writel, + .write_w = bcm2835_sdhci_writew, + .write_b = bcm2835_sdhci_writeb, + .read_l = bcm2835_sdhci_readl, + .read_w = bcm2835_sdhci_readw, + .read_b = bcm2835_sdhci_readb, +}; + +int bcm2835_sdhci_init(u32 regbase, u32 emmc_freq) +{ + struct bcm2835_sdhci_host *bcm_host; + struct sdhci_host *host; + + bcm_host = malloc(sizeof(*bcm_host)); + if (!bcm_host) { + printf("sdhci_host malloc fail!\n"); + return 1; + } + + /* + * See the comments in bcm2835_sdhci_raw_writel(). + * + * This should probably be dynamically calculated based on the actual + * frequency. However, this is the longest we'll have to wait, and + * doesn't seem to slow access down too much, so the added complexity + * doesn't seem worth it for now. + * + * 1/MIN_FREQ is (max) time per tick of eMMC clock. + * 2/MIN_FREQ is time for two ticks. + * Multiply by 1000000 to get uS per two ticks. + * +1 for hack rounding. + */ + bcm_host->twoticks_delay = ((2 * 1000000) / MIN_FREQ) + 1; + bcm_host->last_write = 0; + + host = &bcm_host->host; + host->name = "bcm2835_sdhci"; + host->ioaddr = (void *)regbase; + host->quirks = SDHCI_QUIRK_BROKEN_VOLTAGE | SDHCI_QUIRK_BROKEN_R1B | + SDHCI_QUIRK_WAIT_SEND_CMD; + host->voltages = MMC_VDD_32_33 | MMC_VDD_33_34 | MMC_VDD_165_195; + host->ops = &bcm2835_ops; + + host->version = sdhci_readw(host, SDHCI_HOST_VERSION); + add_sdhci(host, emmc_freq, MIN_FREQ); + + return 0; +} |