diff options
Diffstat (limited to 'drivers/mmc/host/sdhci-bcm2835.c')
| -rw-r--r-- | drivers/mmc/host/sdhci-bcm2835.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/drivers/mmc/host/sdhci-bcm2835.c b/drivers/mmc/host/sdhci-bcm2835.c new file mode 100644 index 000000000..0ef0343c6 --- /dev/null +++ b/drivers/mmc/host/sdhci-bcm2835.c @@ -0,0 +1,202 @@ +/* + * BCM2835 SDHCI + * Copyright (C) 2012 Stephen Warren + * Based on U-Boot's MMC driver for the BCM2835 by Oleksandr Tymoshenko & me + * Portions of the code there were obviously based on the Linux kernel at: + * git://github.com/raspberrypi/linux.git rpi-3.6.y + * commit f5b930b "Main bcm2708 linux port" signed-off-by Dom Cobley. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope 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, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/delay.h> +#include <linux/module.h> +#include <linux/mmc/host.h> +#include "sdhci-pltfm.h" + +/* + * 400KHz is max freq for card ID etc. Use that as min card clock. We need to + * know the min to enable static calculation of max BCM2835_SDHCI_WRITE_DELAY. + */ +#define MIN_FREQ 400000 + +/* + * 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. + * + * This should probably be dynamically calculated based on the actual card + * 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. + * *1000000 for uSecs. + * +1 for hack rounding. + */ +#define BCM2835_SDHCI_WRITE_DELAY (((2 * 1000000) / MIN_FREQ) + 1) + +struct bcm2835_sdhci { + u32 shadow; +}; + +static void bcm2835_sdhci_writel(struct sdhci_host *host, u32 val, int reg) +{ + writel(val, host->ioaddr + reg); + + udelay(BCM2835_SDHCI_WRITE_DELAY); +} + +static inline u32 bcm2835_sdhci_readl(struct sdhci_host *host, int reg) +{ + u32 val = readl(host->ioaddr + reg); + + if (reg == SDHCI_CAPABILITIES) + val |= SDHCI_CAN_VDD_330; + + return val; +} + +static void bcm2835_sdhci_writew(struct sdhci_host *host, u16 val, int reg) +{ + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); + struct bcm2835_sdhci *bcm2835_host = pltfm_host->priv; + u32 oldval = (reg == SDHCI_COMMAND) ? bcm2835_host->shadow : + bcm2835_sdhci_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) + bcm2835_host->shadow = newval; + else + bcm2835_sdhci_writel(host, newval, reg & ~3); +} + +static u16 bcm2835_sdhci_readw(struct sdhci_host *host, int reg) +{ + u32 val = bcm2835_sdhci_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 void bcm2835_sdhci_writeb(struct sdhci_host *host, u8 val, int reg) +{ + u32 oldval = bcm2835_sdhci_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_writel(host, newval, reg & ~3); +} + +static u8 bcm2835_sdhci_readb(struct sdhci_host *host, int reg) +{ + u32 val = bcm2835_sdhci_readl(host, (reg & ~3)); + u32 byte_num = reg & 3; + u32 byte_shift = byte_num * 8; + u32 byte = (val >> byte_shift) & 0xff; + + return byte; +} + +static unsigned int bcm2835_sdhci_get_min_clock(struct sdhci_host *host) +{ + return MIN_FREQ; +} + +static const struct sdhci_ops bcm2835_sdhci_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, + .set_clock = sdhci_set_clock, + .get_max_clock = sdhci_pltfm_clk_get_max_clock, + .get_min_clock = bcm2835_sdhci_get_min_clock, + .set_bus_width = sdhci_set_bus_width, + .reset = sdhci_reset, + .set_uhs_signaling = sdhci_set_uhs_signaling, +}; + +static const struct sdhci_pltfm_data bcm2835_sdhci_pdata = { + .quirks = SDHCI_QUIRK_BROKEN_CARD_DETECTION | + SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK, + .ops = &bcm2835_sdhci_ops, +}; + +static int bcm2835_sdhci_probe(struct platform_device *pdev) +{ + struct sdhci_host *host; + struct bcm2835_sdhci *bcm2835_host; + struct sdhci_pltfm_host *pltfm_host; + int ret; + + host = sdhci_pltfm_init(pdev, &bcm2835_sdhci_pdata, 0); + if (IS_ERR(host)) + return PTR_ERR(host); + + bcm2835_host = devm_kzalloc(&pdev->dev, sizeof(*bcm2835_host), + GFP_KERNEL); + if (!bcm2835_host) { + dev_err(mmc_dev(host->mmc), + "failed to allocate bcm2835_sdhci\n"); + return -ENOMEM; + } + + pltfm_host = sdhci_priv(host); + pltfm_host->priv = bcm2835_host; + + pltfm_host->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(pltfm_host->clk)) { + ret = PTR_ERR(pltfm_host->clk); + goto err; + } + + return sdhci_add_host(host); + +err: + sdhci_pltfm_free(pdev); + return ret; +} + +static const struct of_device_id bcm2835_sdhci_of_match[] = { + { .compatible = "brcm,bcm2835-sdhci" }, + { } +}; +MODULE_DEVICE_TABLE(of, bcm2835_sdhci_of_match); + +static struct platform_driver bcm2835_sdhci_driver = { + .driver = { + .name = "sdhci-bcm2835", + .of_match_table = bcm2835_sdhci_of_match, + .pm = SDHCI_PLTFM_PMOPS, + }, + .probe = bcm2835_sdhci_probe, + .remove = sdhci_pltfm_unregister, +}; +module_platform_driver(bcm2835_sdhci_driver); + +MODULE_DESCRIPTION("BCM2835 SDHCI driver"); +MODULE_AUTHOR("Stephen Warren"); +MODULE_LICENSE("GPL v2"); |