[U-Boot] [PATCH 1/2] mmc: add bcm2835 driver

[Vikram Narayanan]

Some nitpicks.

On 10/24/2012 10:20 AM, Stephen Warren wrote:
> 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-3.2.27
>
> No s-o-b tags were present in either location.
>
> 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().
> * Simplified and commented twoticks_delay calculation.
> * checkpatch fixes.
>
> Cc: Oleksandr Tymoshenko<gonzo at bluezbox.com>
> Signed-off-by: Stephen Warren<swarren at wwwdotorg.org>
> ---
> This series is based on the previous bcm2835 patches I sent, to add the
> mbox and video drivers. Patch 1 should be independant, but patch 2 depends
> on those other patches.
>
>   arch/arm/include/asm/arch-bcm2835/sdhci.h |   24 ++++
>   drivers/mmc/Makefile                      |    1 +
>   drivers/mmc/bcm2835_sdhci.c               |  172 +++++++++++++++++++++++++++++
>   3 files changed, 197 insertions(+)
>   create mode 100644 arch/arm/include/asm/arch-bcm2835/sdhci.h
>   create mode 100644 drivers/mmc/bcm2835_sdhci.c
>
> diff --git a/arch/arm/include/asm/arch-bcm2835/sdhci.h b/arch/arm/include/asm/arch-bcm2835/sdhci.h
> new file mode 100644
> index 0000000..a4f867b
> --- /dev/null
> +++ b/arch/arm/include/asm/arch-bcm2835/sdhci.h
> @@ -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
> diff --git a/drivers/mmc/Makefile b/drivers/mmc/Makefile
> index a1dd730..6be36f2 100644
> --- a/drivers/mmc/Makefile
> +++ b/drivers/mmc/Makefile
> @@ -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
> diff --git a/drivers/mmc/bcm2835_sdhci.c b/drivers/mmc/bcm2835_sdhci.c
> new file mode 100644
> index 0000000..1d623c0
> --- /dev/null
> +++ b/drivers/mmc/bcm2835_sdhci.c
> @@ -0,0 +1,172 @@
> +/*
> + * 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-3.2.27
> + *
> + * 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
> +
> +static uint twoticks_delay;
> +
> +static inline void bcm2835_sdhci_raw_writel(struct sdhci_host *host, u32 val,
> +						int reg)
> +{
> +	static ulong last_write;
> +
> +	/*
> +	 * 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(last_write)<  twoticks_delay)
> +		;
> +
> +	writel(val, host->ioaddr + reg);
> +	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 p = reg == SDHCI_COMMAND ? shadow :
> +		bcm2835_sdhci_raw_readl(host, reg&  ~3);
> +	u32 s = reg<<  3&  0x18;
> +	u32 l = val<<  s;
> +	u32 m = 0xffff<<  s;
> +
> +	if (reg == SDHCI_TRANSFER_MODE)
> +		shadow = (p&  ~m) | l;
> +	else
> +		bcm2835_sdhci_raw_writel(host, (p&  ~m) | l, reg&  ~3);
> +}
> +
> +static void bcm2835_sdhci_writeb(struct sdhci_host *host, u8 val, int reg)
> +{
> +	u32 p = bcm2835_sdhci_raw_readl(host, reg&  ~3);
> +	u32 s = reg<<  3&  0x18;
> +	u32 l = val<<  s;
> +	u32 m = 0xff<<  s;
> +
> +	bcm2835_sdhci_raw_writel(host, (p&  ~m) | l, 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));
> +	val = val>>  (reg<<  3&  0x18)&  0xffff;
> +
> +	return (u16)val;
> +}
> +
> +static u8 bcm2835_sdhci_readb(struct sdhci_host *host, int reg)
> +{
> +	u32 val = bcm2835_sdhci_raw_readl(host, (reg&  ~3));
> +	val = val>>  (reg<<  3&  0x18)&  0xff;
> +
> +	return (u8)val;
> +}

Can the above used magics be made as macros?

~Vikram