--- /dev/null
+/*
+ * Copyright 2005-2008 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright 2008 Luotao Fu, kernel@pengutronix.de
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+#include "../w1_log.h"
+
+/* According to the mx27 Datasheet the reset procedure should take up to about
+ * 1350us. We set the timeout to 500*100us = 50ms for sure */
+#define MXC_W1_RESET_TIMEOUT 500
+
+/*
+ * MXC W1 Register offsets
+ */
+#define MXC_W1_CONTROL 0x00
+#define MXC_W1_TIME_DIVIDER 0x02
+#define MXC_W1_RESET 0x04
+#define MXC_W1_COMMAND 0x06
+#define MXC_W1_TXRX 0x08
+#define MXC_W1_INTERRUPT 0x0A
+#define MXC_W1_INTERRUPT_EN 0x0C
+
+struct mxc_w1_device {
+ void __iomem *regs;
+ unsigned int clkdiv;
+ struct clk *clk;
+ struct w1_bus_master bus_master;
+};
+
+/*
+ * this is the low level routine to
+ * reset the device on the One Wire interface
+ * on the hardware
+ */
+static u8 mxc_w1_ds2_reset_bus(void *data)
+{
+ u8 reg_val;
+ unsigned int timeout_cnt = 0;
+ struct mxc_w1_device *dev = data;
+
+ __raw_writeb(0x80, (dev->regs + MXC_W1_CONTROL));
+
+ while (1) {
+ reg_val = __raw_readb(dev->regs + MXC_W1_CONTROL);
+
+ if (((reg_val >> 7) & 0x1) == 0 ||
+ timeout_cnt > MXC_W1_RESET_TIMEOUT)
+ break;
+ else
+ timeout_cnt++;
+
+ udelay(100);
+ }
+ return (reg_val >> 7) & 0x1;
+}
+
+/*
+ * this is the low level routine to read/write a bit on the One Wire
+ * interface on the hardware. It does write 0 if parameter bit is set
+ * to 0, otherwise a write 1/read.
+ */
+static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
+{
+ struct mxc_w1_device *mdev = data;
+ void __iomem *ctrl_addr = mdev->regs + MXC_W1_CONTROL;
+ unsigned int timeout_cnt = 400; /* Takes max. 120us according to
+ * datasheet.
+ */
+
+ __raw_writeb((1 << (5 - bit)), ctrl_addr);
+
+ while (timeout_cnt--) {
+ if (!((__raw_readb(ctrl_addr) >> (5 - bit)) & 0x1))
+ break;
+
+ udelay(1);
+ }
+
+ return ((__raw_readb(ctrl_addr)) >> 3) & 0x1;
+}
+
+static int __init mxc_w1_probe(struct platform_device *pdev)
+{
+ struct mxc_w1_device *mdev;
+ struct resource *res;
+ int err = 0;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
+ mdev = kzalloc(sizeof(struct mxc_w1_device), GFP_KERNEL);
+ if (!mdev)
+ return -ENOMEM;
+
+ mdev->clk = clk_get(&pdev->dev, "owire_clk");
+ if (!mdev->clk) {
+ err = -ENODEV;
+ goto failed_clk;
+ }
+
+ mdev->clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1;
+
+ res = request_mem_region(res->start, resource_size(res),
+ "mxc_w1");
+ if (!res) {
+ err = -EBUSY;
+ goto failed_req;
+ }
+
+ mdev->regs = ioremap(res->start, resource_size(res));
+ if (!mdev->regs) {
+ printk(KERN_ERR "Cannot map frame buffer registers\n");
+ goto failed_ioremap;
+ }
+
+ clk_enable(mdev->clk);
+ __raw_writeb(mdev->clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER);
+
+ mdev->bus_master.data = mdev;
+ mdev->bus_master.reset_bus = mxc_w1_ds2_reset_bus;
+ mdev->bus_master.touch_bit = mxc_w1_ds2_touch_bit;
+
+ err = w1_add_master_device(&mdev->bus_master);
+
+ if (err)
+ goto failed_add;
+
+ platform_set_drvdata(pdev, mdev);
+ return 0;
+
+failed_add:
+ iounmap(mdev->regs);
+failed_ioremap:
+ release_mem_region(res->start, resource_size(res));
+failed_req:
+ clk_put(mdev->clk);
+failed_clk:
+ kfree(mdev);
+ return err;
+}
+
+/*
+ * disassociate the w1 device from the driver
+ */
+static int mxc_w1_remove(struct platform_device *pdev)
+{
+ struct mxc_w1_device *mdev = platform_get_drvdata(pdev);
+ struct resource *res;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+ w1_remove_master_device(&mdev->bus_master);
+
+ iounmap(mdev->regs);
+ release_mem_region(res->start, resource_size(res));
+ clk_disable(mdev->clk);
+ clk_put(mdev->clk);
+
+ platform_set_drvdata(pdev, NULL);
+
+ return 0;
+}
+
+static struct platform_driver mxc_w1_driver = {
+ .driver = {
+ .name = "mxc_w1",
+ },
+ .probe = mxc_w1_probe,
+ .remove = mxc_w1_remove,
+};
+
+static int __init mxc_w1_init(void)
+{
+ return platform_driver_register(&mxc_w1_driver);
+}
+
+static void mxc_w1_exit(void)
+{
+ platform_driver_unregister(&mxc_w1_driver);
+}
+
+module_init(mxc_w1_init);
+module_exit(mxc_w1_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Freescale Semiconductors Inc");
+MODULE_DESCRIPTION("Driver for One-Wire on MXC");
projects / kernel / kernel-generic.git / commitdiff