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mmc: add bcm2835 driver 

This adds a simple driver for the BCM2835's SD controller.

Workarounds are implemented for:
* Register writes can't be too close to each-other in time, or they will
  be lost.
* Register accesses must all be 32-bit, so implement custom accessors.

This code was extracted from:
git://github.com/gonzoua/u-boot-pi.git master
which was created by Oleksandr Tymoshenko.

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.

swarren changed the following for upstream:
* Removed hack udelay()s in bcm2835_sdhci_raw_writel(); setting
  SDHCI_QUIRK_WAIT_SEND_CMD appears to solve the issues.
* Remove register logging from read*/write* functions.
* Sort out confusion with min/max_freq values passed to add_sdhci().
* Use more descriptive variable names and calculations in IO accessors.
* Simplified and commented twoticks_delay calculation.
* checkpatch fixes.

Cc: Andy Fleming <afleming@gmail.com>
Signed-off-by: Oleksandr Tymoshenko <gonzo@bluezbox.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Andy Fleming <afleming@gmail.com>
This commit is contained in:
Stephen Warren 2013-01-29 16:37:41 +00:00 committed by Albert ARIBAUD
parent 6be3c9fca2
commit 9a4fbe4fbd
3 changed files with 214 additions and 0 deletions
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24
arch/arm/include/asm/arch-bcm2835/sdhci.h Normal file
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@ -0,0 +1,24 @@
/*
* (C) Copyright 2012 Stephen Warren
*
* See file CREDITS for list of people who contributed to this
* project.
*
* 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.
*/
#ifndef _BCM2835_SDHCI_H_
#define _BCM2835_SDHCI_H_
#define BCM2835_SDHCI_BASE 0x20300000
int bcm2835_sdhci_init(u32 regbase, u32 emmc_freq);
#endif

1
drivers/mmc/Makefile
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@ -43,6 +43,7 @@ COBJS-$(CONFIG_MXS_MMC) += mxsmmc.o
COBJS-$(CONFIG_OMAP_HSMMC) += omap_hsmmc.o
COBJS-$(CONFIG_PXA_MMC_GENERIC) += pxa_mmc_gen.o
COBJS-$(CONFIG_SDHCI) += sdhci.o
COBJS-$(CONFIG_BCM2835_SDHCI) += bcm2835_sdhci.o
COBJS-$(CONFIG_S5P_SDHCI) += s5p_sdhci.o
COBJS-$(CONFIG_SH_MMCIF) += sh_mmcif.o
COBJS-$(CONFIG_TEGRA_MMC) += tegra_mmc.o

189
drivers/mmc/bcm2835_sdhci.c Normal file
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@ -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;
}