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-3.2.27

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<[email protected]>

Signed-off-by Stephen Warren<[email protected]>

---
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

arch/arm/include/asm/arch-bcm2835/sdhci.h new file +24 -0

new file mode 100644
index 0000000..a4f867b
@@ -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

drivers/mmc/Makefile +1 -0

index a1dd730..6be36f2 100644
@@ -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

drivers/mmc/bcm2835_sdhci.c new file +115 -0

new file mode 100644
index 0000000..1d623c0
@@ -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;
+

Some nitpicks.

Quoted 6 lines · Stephen Warren

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.

drivers/mmc/bcm2835_sdhci.c line 125

Quoted 7 lines

drivers/mmc/bcm2835_sdhci.c new file +7 -0

+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?

Quoted 3 lines · Vikram Narayanan

Some nitpicks.

On 10/24/2012 10:20 AM, Stephen Warren wrote:

Quoted 9 lines

drivers/mmc/bcm2835_sdhci.c line 125

Quoted 7 lines

drivers/mmc/bcm2835_sdhci.c new file +7 -0

+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?

This code was taken directly from the downstream Linux kernel, so I changed it as little as possible, to make comparisons easier. Still, if people want I can certainly make it easier to understand the expression a bit.

I don't think the issue is the magic numbers so much as understanding what the expression does; the magic are obvious then. It's simply extracting byte n from from a u32. Would the following be more obvious:

byte_num = reg& 3;
byte_shift = bytenum * 8;
byte = (val>> byte_shift)& 0xff;

... and similar for the other functions?

Quoted 4 lines · Stephen Warren

Quoted 3 lines · Vikram Narayanan

Some nitpicks.

On 10/24/2012 10:20 AM, Stephen Warren wrote:

<snip>

Quoted 10 lines

Quoted 9 lines

drivers/mmc/bcm2835_sdhci.c line 125

Quoted 7 lines

drivers/mmc/bcm2835_sdhci.c new file +7 -0

+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?

Quoted 4 lines

This code was taken directly from the downstream Linux kernel, so I changed it as little as possible, to make comparisons easier. Still, if people want I can certainly make it easier to understand the expression a bit.

Seems reasonable.

Quoted 4 lines

I don't think the issue is the magic numbers so much as understanding what the expression does; the magic are obvious then. It's simply extracting byte n from from a u32. Would the following be more obvious:

Quoted 5 lines

byte_num = reg& 3;
byte_shift = bytenum * 8;
byte = (val>> byte_shift)& 0xff;

... and similar for the other functions?

This looks better to me than the former. Thanks.

Hi Stephen,

Quoted 33 lines · Vikram Narayanan

Quoted 4 lines · Stephen Warren

Quoted 3 lines · Vikram Narayanan

Some nitpicks.

On 10/24/2012 10:20 AM, Stephen Warren wrote:

<snip>

Quoted 10 lines

Quoted 9 lines

drivers/mmc/bcm2835_sdhci.c line 125

Quoted 7 lines

drivers/mmc/bcm2835_sdhci.c new file +7 -0

+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?

Quoted 4 lines

This code was taken directly from the downstream Linux kernel, so I changed it as little as possible, to make comparisons easier. Still, if people want I can certainly make it easier to understand the expression a bit.

Seems reasonable.

Quoted 9 lines

I don't think the issue is the magic numbers so much as understanding what the expression does; the magic are obvious then. It's simply extracting byte n from from a u32. Would the following be more obvious:

byte_num = reg& 3;
byte_shift = bytenum * 8;
byte = (val>> byte_shift)& 0xff;

... and similar for the other functions?

Quoted 1 line

This looks better to me than the former. Thanks.

Stephen,

Does this mean there'll be a new version of this patch?

Amicalement,

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.

Quoted 11 lines · Stephen Warren

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.

Quoted 4 lines

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.

Um, that's a bit worrying to me. Wolfgang?

Quoted 14 lines · Tom Rini

Quoted 13 lines · Stephen Warren

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

Quoted 2 lines

Quoted 1 line

No s-o-b tags were present in either location.

Um, that's a bit worrying to me. Wolfgang?

I didn't have much experience with s-o-b stuff, so excuse my ignorance. Is there official procedure, or is it enough to state that I sign off on everything in
git://github.com/gonzoua/u-boot-pi.git master authored by me?

Quoted 17 lines · Oleksandr Tymoshenko

Quoted 16 lines · Tom Rini

Quoted 14 lines · Stephen Warren

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

Quoted 7 lines

Quoted 2 lines

Quoted 1 line

No s-o-b tags were present in either location.

Um, that's a bit worrying to me. Wolfgang?

I didn't have much experience with s-o-b stuff, so excuse my ignorance. Is there official procedure, or is it enough to state that I sign off on everything in
git://github.com/gonzoua/u-boot-pi.git master authored by me?

Just about. Please read
http://elinux.org/Developer_Certificate_Of_Origin and then assuming that is all true, reply to this email with a properly formatted Signed-off-by line (and then hey, you end up in the contributors for the next U-Boot release, once the code is merged). And then you can get in the habit of doing 'git commit -s' for projects where the above applies. There's still a question about the portions taken from the kernel tree. Thanks!

Quoted 12 lines · Tom Rini

Quoted 11 lines · Stephen Warren

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.

Quoted 5 lines

Quoted 4 lines

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.

Um, that's a bit worrying to me. Wolfgang?

I didn't have much experience with s-o-b stuff, so excuse my ignorance.