LXR linux/drivers/mmc/host/sdhci-bcm2835.c

   1/*
   2 * BCM2835 SDHCI
   3 * Copyright (C) 2012 Stephen Warren
   4 * Based on U-Boot's MMC driver for the BCM2835 by Oleksandr Tymoshenko & me
   5 * Portions of the code there were obviously based on the Linux kernel at:
   6 * git://github.com/raspberrypi/linux.git rpi-3.6.y
   7 * commit f5b930b "Main bcm2708 linux port" signed-off-by Dom Cobley.
   8 *
   9 * This program is free software; you can redistribute it and/or modify it
  10 * under the terms and conditions of the GNU General Public License,
  11 * version 2, as published by the Free Software Foundation.
  12 *
  13 * This program is distributed in the hope it will be useful, but WITHOUT
  14 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  16 * more details.
  17 *
  18 * You should have received a copy of the GNU General Public License
  19 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22#include <linux/delay.h>
  23#include <linux/module.h>
  24#include <linux/mmc/host.h>
  25#include "sdhci-pltfm.h"
  26
  27/*
  28 * 400KHz is max freq for card ID etc. Use that as min card clock. We need to
  29 * know the min to enable static calculation of max BCM2835_SDHCI_WRITE_DELAY.
  30 */
  31#define MIN_FREQ 400000
  32
  33/*
  34 * The Arasan has a bugette whereby it may lose the content of successive
  35 * writes to registers that are within two SD-card clock cycles of each other
  36 * (a clock domain crossing problem). It seems, however, that the data
  37 * register does not have this problem, which is just as well - otherwise we'd
  38 * have to nobble the DMA engine too.
  39 *
  40 * This should probably be dynamically calculated based on the actual card
  41 * frequency. However, this is the longest we'll have to wait, and doesn't
  42 * seem to slow access down too much, so the added complexity doesn't seem
  43 * worth it for now.
  44 *
  45 * 1/MIN_FREQ is (max) time per tick of eMMC clock.
  46 * 2/MIN_FREQ is time for two ticks.
  47 * Multiply by 1000000 to get uS per two ticks.
  48 * *1000000 for uSecs.
  49 * +1 for hack rounding.
  50 */
  51#define BCM2835_SDHCI_WRITE_DELAY       (((2 * 1000000) / MIN_FREQ) + 1)
  52
  53struct bcm2835_sdhci {
  54        u32 shadow;
  55};
  56
  57static void bcm2835_sdhci_writel(struct sdhci_host *host, u32 val, int reg)
  58{
  59        writel(val, host->ioaddr + reg);
  60
  61        udelay(BCM2835_SDHCI_WRITE_DELAY);
  62}
  63
  64static inline u32 bcm2835_sdhci_readl(struct sdhci_host *host, int reg)
  65{
  66        u32 val = readl(host->ioaddr + reg);
  67
  68        if (reg == SDHCI_CAPABILITIES)
  69                val |= SDHCI_CAN_VDD_330;
  70
  71        return val;
  72}
  73
  74static void bcm2835_sdhci_writew(struct sdhci_host *host, u16 val, int reg)
  75{
  76        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
  77        struct bcm2835_sdhci *bcm2835_host = pltfm_host->priv;
  78        u32 oldval = (reg == SDHCI_COMMAND) ? bcm2835_host->shadow :
  79                bcm2835_sdhci_readl(host, reg & ~3);
  80        u32 word_num = (reg >> 1) & 1;
  81        u32 word_shift = word_num * 16;
  82        u32 mask = 0xffff << word_shift;
  83        u32 newval = (oldval & ~mask) | (val << word_shift);
  84
  85        if (reg == SDHCI_TRANSFER_MODE)
  86                bcm2835_host->shadow = newval;
  87        else
  88                bcm2835_sdhci_writel(host, newval, reg & ~3);
  89}
  90
  91static u16 bcm2835_sdhci_readw(struct sdhci_host *host, int reg)
  92{
  93        u32 val = bcm2835_sdhci_readl(host, (reg & ~3));
  94        u32 word_num = (reg >> 1) & 1;
  95        u32 word_shift = word_num * 16;
  96        u32 word = (val >> word_shift) & 0xffff;
  97
  98        return word;
  99}
 100
 101static void bcm2835_sdhci_writeb(struct sdhci_host *host, u8 val, int reg)
 102{
 103        u32 oldval = bcm2835_sdhci_readl(host, reg & ~3);
 104        u32 byte_num = reg & 3;
 105        u32 byte_shift = byte_num * 8;
 106        u32 mask = 0xff << byte_shift;
 107        u32 newval = (oldval & ~mask) | (val << byte_shift);
 108
 109        bcm2835_sdhci_writel(host, newval, reg & ~3);
 110}
 111
 112static u8 bcm2835_sdhci_readb(struct sdhci_host *host, int reg)
 113{
 114        u32 val = bcm2835_sdhci_readl(host, (reg & ~3));
 115        u32 byte_num = reg & 3;
 116        u32 byte_shift = byte_num * 8;
 117        u32 byte = (val >> byte_shift) & 0xff;
 118
 119        return byte;
 120}
 121
 122static unsigned int bcm2835_sdhci_get_min_clock(struct sdhci_host *host)
 123{
 124        return MIN_FREQ;
 125}
 126
 127static const struct sdhci_ops bcm2835_sdhci_ops = {
 128        .write_l = bcm2835_sdhci_writel,
 129        .write_w = bcm2835_sdhci_writew,
 130        .write_b = bcm2835_sdhci_writeb,
 131        .read_l = bcm2835_sdhci_readl,
 132        .read_w = bcm2835_sdhci_readw,
 133        .read_b = bcm2835_sdhci_readb,
 134        .set_clock = sdhci_set_clock,
 135        .get_max_clock = sdhci_pltfm_clk_get_max_clock,
 136        .get_min_clock = bcm2835_sdhci_get_min_clock,
 137        .set_bus_width = sdhci_set_bus_width,
 138        .reset = sdhci_reset,
 139        .set_uhs_signaling = sdhci_set_uhs_signaling,
 140};
 141
 142static const struct sdhci_pltfm_data bcm2835_sdhci_pdata = {
 143        .quirks = SDHCI_QUIRK_BROKEN_CARD_DETECTION |
 144                  SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK,
 145        .ops = &bcm2835_sdhci_ops,
 146};
 147
 148static int bcm2835_sdhci_probe(struct platform_device *pdev)
 149{
 150        struct sdhci_host *host;
 151        struct bcm2835_sdhci *bcm2835_host;
 152        struct sdhci_pltfm_host *pltfm_host;
 153        int ret;
 154
 155        host = sdhci_pltfm_init(pdev, &bcm2835_sdhci_pdata, 0);
 156        if (IS_ERR(host))
 157                return PTR_ERR(host);
 158
 159        bcm2835_host = devm_kzalloc(&pdev->dev, sizeof(*bcm2835_host),
 160                                        GFP_KERNEL);
 161        if (!bcm2835_host) {
 162                dev_err(mmc_dev(host->mmc),
 163                        "failed to allocate bcm2835_sdhci\n");
 164                return -ENOMEM;
 165        }
 166
 167        pltfm_host = sdhci_priv(host);
 168        pltfm_host->priv = bcm2835_host;
 169
 170        pltfm_host->clk = devm_clk_get(&pdev->dev, NULL);
 171        if (IS_ERR(pltfm_host->clk)) {
 172                ret = PTR_ERR(pltfm_host->clk);
 173                goto err;
 174        }
 175
 176        return sdhci_add_host(host);
 177
 178err:
 179        sdhci_pltfm_free(pdev);
 180        return ret;
 181}
 182
 183static int bcm2835_sdhci_remove(struct platform_device *pdev)
 184{
 185        return sdhci_pltfm_unregister(pdev);
 186}
 187
 188static const struct of_device_id bcm2835_sdhci_of_match[] = {
 189        { .compatible = "brcm,bcm2835-sdhci" },
 190        { }
 191};
 192MODULE_DEVICE_TABLE(of, bcm2835_sdhci_of_match);
 193
 194static struct platform_driver bcm2835_sdhci_driver = {
 195        .driver = {
 196                .name = "sdhci-bcm2835",
 197                .of_match_table = bcm2835_sdhci_of_match,
 198                .pm = SDHCI_PLTFM_PMOPS,
 199        },
 200        .probe = bcm2835_sdhci_probe,
 201        .remove = bcm2835_sdhci_remove,
 202};
 203module_platform_driver(bcm2835_sdhci_driver);
 204
 205MODULE_DESCRIPTION("BCM2835 SDHCI driver");
 206MODULE_AUTHOR("Stephen Warren");
 207MODULE_LICENSE("GPL v2");
 208