--- /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.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+
+/*
+ * MXC W1 Register offsets
+ */
+#define MXC_W1_CONTROL 0x00
+# define MXC_W1_CONTROL_RDST BIT(3)
+# define MXC_W1_CONTROL_WR(x) BIT(5 - (x))
+# define MXC_W1_CONTROL_PST BIT(6)
+# define MXC_W1_CONTROL_RPP BIT(7)
+#define MXC_W1_TIME_DIVIDER 0x02
+#define MXC_W1_RESET 0x04
+# define MXC_W1_RESET_RST BIT(0)
+
+struct mxc_w1_device {
+ void __iomem *regs;
+ 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)
+{
+ struct mxc_w1_device *dev = data;
+ unsigned long timeout;
+
+ writeb(MXC_W1_CONTROL_RPP, dev->regs + MXC_W1_CONTROL);
+
+ /* Wait for reset sequence 511+512us, use 1500us for sure */
+ timeout = jiffies + usecs_to_jiffies(1500);
+
+ udelay(511 + 512);
+
+ do {
+ u8 ctrl = readb(dev->regs + MXC_W1_CONTROL);
+
+ /* PST bit is valid after the RPP bit is self-cleared */
+ if (!(ctrl & MXC_W1_CONTROL_RPP))
+ return !(ctrl & MXC_W1_CONTROL_PST);
+ } while (time_is_after_jiffies(timeout));
+
+ return 1;
+}
+
+/*
+ * 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 *dev = data;
+ unsigned long timeout;
+
+ writeb(MXC_W1_CONTROL_WR(bit), dev->regs + MXC_W1_CONTROL);
+
+ /* Wait for read/write bit (60us, Max 120us), use 200us for sure */
+ timeout = jiffies + usecs_to_jiffies(200);
+
+ udelay(60);
+
+ do {
+ u8 ctrl = readb(dev->regs + MXC_W1_CONTROL);
+
+ /* RDST bit is valid after the WR1/RD bit is self-cleared */
+ if (!(ctrl & MXC_W1_CONTROL_WR(bit)))
+ return !!(ctrl & MXC_W1_CONTROL_RDST);
+ } while (time_is_after_jiffies(timeout));
+
+ return 0;
+}
+
+static int mxc_w1_probe(struct platform_device *pdev)
+{
+ struct mxc_w1_device *mdev;
+ unsigned long clkrate;
+ struct resource *res;
+ unsigned int clkdiv;
+ int err;
+
+ mdev = devm_kzalloc(&pdev->dev, sizeof(struct mxc_w1_device),
+ GFP_KERNEL);
+ if (!mdev)
+ return -ENOMEM;
+
+ mdev->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(mdev->clk))
+ return PTR_ERR(mdev->clk);
+
+ clkrate = clk_get_rate(mdev->clk);
+ if (clkrate < 10000000)
+ dev_warn(&pdev->dev,
+ "Low clock frequency causes improper function\n");
+
+ clkdiv = DIV_ROUND_CLOSEST(clkrate, 1000000);
+ clkrate /= clkdiv;
+ if ((clkrate < 980000) || (clkrate > 1020000))
+ dev_warn(&pdev->dev,
+ "Incorrect time base frequency %lu Hz\n", clkrate);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ mdev->regs = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(mdev->regs))
+ return PTR_ERR(mdev->regs);
+
+ err = clk_prepare_enable(mdev->clk);
+ if (err)
+ return err;
+
+ /* Software reset 1-Wire module */
+ writeb(MXC_W1_RESET_RST, mdev->regs + MXC_W1_RESET);
+ writeb(0, mdev->regs + MXC_W1_RESET);
+
+ writeb(clkdiv - 1, 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;
+
+ platform_set_drvdata(pdev, mdev);
+
+ err = w1_add_master_device(&mdev->bus_master);
+ if (err)
+ clk_disable_unprepare(mdev->clk);
+
+ 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);
+
+ w1_remove_master_device(&mdev->bus_master);
+
+ clk_disable_unprepare(mdev->clk);
+
+ return 0;
+}
+
+static const struct of_device_id mxc_w1_dt_ids[] = {
+ { .compatible = "fsl,imx21-owire" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mxc_w1_dt_ids);
+
+static struct platform_driver mxc_w1_driver = {
+ .driver = {
+ .name = "mxc_w1",
+ .of_match_table = mxc_w1_dt_ids,
+ },
+ .probe = mxc_w1_probe,
+ .remove = mxc_w1_remove,
+};
+module_platform_driver(mxc_w1_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Freescale Semiconductors Inc");
+MODULE_DESCRIPTION("Driver for One-Wire on MXC");
Code Review / kvmfornfv.git / blobdiff