[PATCH] mmc: add BCM2835 driver
Stephen Warren
swarren at wwwdotorg.org
Thu Jan 3 00:34:49 EST 2013
Add a very simple driver for the BCM2835 SoC, which is used in the
Raspberry Pi board.
Signed-off-by: Stephen Warren <swarren at wwwdotorg.org>
---
.../devicetree/bindings/mmc/brcm,bcm2835-sdhci.txt | 18 ++
drivers/mmc/host/Kconfig | 11 +
drivers/mmc/host/Makefile | 1 +
drivers/mmc/host/sdhci-bcm2835.c | 227 ++++++++++++++++++++
4 files changed, 257 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mmc/brcm,bcm2835-sdhci.txt
create mode 100644 drivers/mmc/host/sdhci-bcm2835.c
diff --git a/Documentation/devicetree/bindings/mmc/brcm,bcm2835-sdhci.txt b/Documentation/devicetree/bindings/mmc/brcm,bcm2835-sdhci.txt
new file mode 100644
index 0000000..59476fb
--- /dev/null
+++ b/Documentation/devicetree/bindings/mmc/brcm,bcm2835-sdhci.txt
@@ -0,0 +1,18 @@
+Broadcom BCM2835 SDHCI controller
+
+This file documents differences between the core properties described
+by mmc.txt and the properties that represent the BCM2835 controller.
+
+Required properties:
+- compatible : Should be "brcm,bcm2835-sdhci".
+- clocks : The clock feeding the SDHCI controller.
+
+Example:
+
+sdhci: sdhci {
+ compatible = "brcm,bcm2835-sdhci";
+ reg = <0x7e300000 0x100>;
+ interrupts = <2 30>;
+ clocks = <&clk_mmc>;
+ bus-width = <4>;
+};
diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index cc8a8fa..7684f7f 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -238,6 +238,17 @@ config MMC_SDHCI_S3C_DMA
YMMV.
+config MMC_SDHCI_BCM2835
+ tristate "SDHCI platform support for the BCM2835 SD/MMC Controller"
+ depends on ARCH_BCM2835
+ depends on MMC_SDHCI_PLTFM
+ select MMC_SDHCI_IO_ACCESSORS
+ help
+ This selects the BCM2835 SD/MMC controller. If you have a BCM2835
+ platform with SD or MMC devices, say Y or M here.
+
+ If unsure, say N.
+
config MMC_OMAP
tristate "TI OMAP Multimedia Card Interface support"
depends on ARCH_OMAP
diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
index e4e218c..d5ea0722 100644
--- a/drivers/mmc/host/Makefile
+++ b/drivers/mmc/host/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_MMC_SDHCI_DOVE) += sdhci-dove.o
obj-$(CONFIG_MMC_SDHCI_TEGRA) += sdhci-tegra.o
obj-$(CONFIG_MMC_SDHCI_OF_ESDHC) += sdhci-of-esdhc.o
obj-$(CONFIG_MMC_SDHCI_OF_HLWD) += sdhci-of-hlwd.o
+obj-$(CONFIG_MMC_SDHCI_BCM2835) += sdhci-bcm2835.o
ifeq ($(CONFIG_CB710_DEBUG),y)
CFLAGS-cb710-mmc += -DDEBUG
diff --git a/drivers/mmc/host/sdhci-bcm2835.c b/drivers/mmc/host/sdhci-bcm2835.c
new file mode 100644
index 0000000..453825f
--- /dev/null
+++ b/drivers/mmc/host/sdhci-bcm2835.c
@@ -0,0 +1,227 @@
+/*
+ * 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 {
+ struct clk *clk;
+ 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 = pltfm_host->priv;
+ 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_max_clock(struct sdhci_host *host)
+{
+ struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+ struct bcm2835_sdhci *bcm2835_host = pltfm_host->priv;
+
+ return clk_get_rate(bcm2835_host->clk);
+}
+
+unsigned int bcm2835_sdhci_get_min_clock(struct sdhci_host *host)
+{
+ return MIN_FREQ;
+}
+
+unsigned int bcm2835_sdhci_get_timeout_clock(struct sdhci_host *host)
+{
+ struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+ struct bcm2835_sdhci *bcm2835_host = pltfm_host->priv;
+
+ return clk_get_rate(bcm2835_host->clk);
+}
+
+static 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,
+ .get_max_clock = bcm2835_sdhci_get_max_clock,
+ .get_min_clock = bcm2835_sdhci_get_min_clock,
+ .get_timeout_clock = bcm2835_sdhci_get_timeout_clock,
+};
+
+static struct sdhci_pltfm_data bcm2835_sdhci_pdata = {
+ .quirks = SDHCI_QUIRK_BROKEN_CARD_DETECTION,
+ .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);
+ if (IS_ERR(host))
+ return PTR_ERR(host);
+
+ bcm2835_host = devm_kzalloc(&pdev->dev, sizeof(*bcm2835_host),
+ GFP_KERNEL);
+ if (!bcm2835_host) {
+ dev_err(mmc_dev(host->mmc),
+ "failed to allocate bcm2835_sdhci\n");
+ return -ENOMEM;
+ }
+
+ pltfm_host = sdhci_priv(host);
+ pltfm_host->priv = bcm2835_host;
+
+ bcm2835_host->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(bcm2835_host->clk)) {
+ ret = PTR_ERR(bcm2835_host->clk);
+ goto err;
+ }
+
+ return sdhci_add_host(host);
+
+err:
+ sdhci_pltfm_free(pdev);
+ return ret;
+}
+
+static int bcm2835_sdhci_remove(struct platform_device *pdev)
+{
+ struct sdhci_host *host = platform_get_drvdata(pdev);
+ int dead = (readl(host->ioaddr + SDHCI_INT_STATUS) == 0xffffffff);
+
+ sdhci_remove_host(host, dead);
+ sdhci_pltfm_free(pdev);
+
+ return 0;
+}
+
+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",
+ .owner = THIS_MODULE,
+ .of_match_table = bcm2835_sdhci_of_match,
+ .pm = SDHCI_PLTFM_PMOPS,
+ },
+ .probe = bcm2835_sdhci_probe,
+ .remove = bcm2835_sdhci_remove,
+};
+module_platform_driver(bcm2835_sdhci_driver);
+
+MODULE_DESCRIPTION("BCM2835 SDHCI driver");
+MODULE_AUTHOR("Stephen Warren");
+MODULE_LICENSE("GPL v2");
--
1.7.10.4
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