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>
diff --git a/drivers/mmc/bcm2835_sdhci.c b/drivers/mmc/bcm2835_sdhci.c
new file mode 100644
index 0000000..b0afc3c
--- /dev/null
+++ b/drivers/mmc/bcm2835_sdhci.c
@@ -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;
+}