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/*
* 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 = sdhci_pltfm_priv(pltfm_host);
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,
sizeof(*bcm2835_host));
if (IS_ERR(host))
return PTR_ERR(host);
pltfm_host = sdhci_priv(host);
pltfm_host->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(pltfm_host->clk)) {
ret = PTR_ERR(pltfm_host->clk);
goto err;
}
ret = clk_prepare_enable(pltfm_host->clk);
if (ret) {
dev_err(&pdev->dev, "failed to enable host clk\n");
goto err;
}
ret = sdhci_add_host(host);
if (ret)
goto err_clk;
return 0;
err_clk:
clk_disable_unprepare(pltfm_host->clk);
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");
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