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63724bbfb1
The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is ignored (apart from emitting a warning) and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new(), which already returns void. Eventually after all drivers are converted, .remove_new() will be renamed to .remove(). Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/d805f3ccc5bc59584c2575b7b33a56a33f6812c7.1708340114.git.u.kleine-koenig@pengutronix.de Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
182 lines
4.2 KiB
C
182 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright 2005-2008 Freescale Semiconductor, Inc. All Rights Reserved.
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* Copyright 2008 Luotao Fu, kernel@pengutronix.de
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*/
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#include <linux/clk.h>
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#include <linux/delay.h>
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#include <linux/io.h>
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#include <linux/ktime.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/platform_device.h>
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#include <linux/w1.h>
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/*
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* MXC W1 Register offsets
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*/
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#define MXC_W1_CONTROL 0x00
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# define MXC_W1_CONTROL_RDST BIT(3)
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# define MXC_W1_CONTROL_WR(x) BIT(5 - (x))
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# define MXC_W1_CONTROL_PST BIT(6)
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# define MXC_W1_CONTROL_RPP BIT(7)
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#define MXC_W1_TIME_DIVIDER 0x02
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#define MXC_W1_RESET 0x04
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# define MXC_W1_RESET_RST BIT(0)
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struct mxc_w1_device {
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void __iomem *regs;
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struct clk *clk;
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struct w1_bus_master bus_master;
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};
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/*
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* this is the low level routine to
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* reset the device on the One Wire interface
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* on the hardware
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*/
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static u8 mxc_w1_ds2_reset_bus(void *data)
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{
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struct mxc_w1_device *dev = data;
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ktime_t timeout;
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writeb(MXC_W1_CONTROL_RPP, dev->regs + MXC_W1_CONTROL);
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/* Wait for reset sequence 511+512us, use 1500us for sure */
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timeout = ktime_add_us(ktime_get(), 1500);
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udelay(511 + 512);
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do {
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u8 ctrl = readb(dev->regs + MXC_W1_CONTROL);
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/* PST bit is valid after the RPP bit is self-cleared */
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if (!(ctrl & MXC_W1_CONTROL_RPP))
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return !(ctrl & MXC_W1_CONTROL_PST);
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} while (ktime_before(ktime_get(), timeout));
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return 1;
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}
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/*
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* this is the low level routine to read/write a bit on the One Wire
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* interface on the hardware. It does write 0 if parameter bit is set
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* to 0, otherwise a write 1/read.
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*/
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static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
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{
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struct mxc_w1_device *dev = data;
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ktime_t timeout;
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writeb(MXC_W1_CONTROL_WR(bit), dev->regs + MXC_W1_CONTROL);
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/* Wait for read/write bit (60us, Max 120us), use 200us for sure */
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timeout = ktime_add_us(ktime_get(), 200);
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udelay(60);
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do {
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u8 ctrl = readb(dev->regs + MXC_W1_CONTROL);
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/* RDST bit is valid after the WR1/RD bit is self-cleared */
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if (!(ctrl & MXC_W1_CONTROL_WR(bit)))
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return !!(ctrl & MXC_W1_CONTROL_RDST);
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} while (ktime_before(ktime_get(), timeout));
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return 0;
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}
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static int mxc_w1_probe(struct platform_device *pdev)
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{
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struct mxc_w1_device *mdev;
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unsigned long clkrate;
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unsigned int clkdiv;
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int err;
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mdev = devm_kzalloc(&pdev->dev, sizeof(struct mxc_w1_device),
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GFP_KERNEL);
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if (!mdev)
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return -ENOMEM;
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mdev->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(mdev->clk))
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return PTR_ERR(mdev->clk);
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err = clk_prepare_enable(mdev->clk);
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if (err)
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return err;
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clkrate = clk_get_rate(mdev->clk);
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if (clkrate < 10000000)
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dev_warn(&pdev->dev,
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"Low clock frequency causes improper function\n");
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clkdiv = DIV_ROUND_CLOSEST(clkrate, 1000000);
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clkrate /= clkdiv;
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if ((clkrate < 980000) || (clkrate > 1020000))
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dev_warn(&pdev->dev,
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"Incorrect time base frequency %lu Hz\n", clkrate);
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mdev->regs = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(mdev->regs)) {
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err = PTR_ERR(mdev->regs);
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goto out_disable_clk;
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}
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/* Software reset 1-Wire module */
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writeb(MXC_W1_RESET_RST, mdev->regs + MXC_W1_RESET);
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writeb(0, mdev->regs + MXC_W1_RESET);
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writeb(clkdiv - 1, mdev->regs + MXC_W1_TIME_DIVIDER);
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mdev->bus_master.data = mdev;
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mdev->bus_master.reset_bus = mxc_w1_ds2_reset_bus;
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mdev->bus_master.touch_bit = mxc_w1_ds2_touch_bit;
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platform_set_drvdata(pdev, mdev);
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err = w1_add_master_device(&mdev->bus_master);
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if (err)
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goto out_disable_clk;
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return 0;
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out_disable_clk:
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clk_disable_unprepare(mdev->clk);
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return err;
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}
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/*
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* disassociate the w1 device from the driver
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*/
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static void mxc_w1_remove(struct platform_device *pdev)
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{
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struct mxc_w1_device *mdev = platform_get_drvdata(pdev);
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w1_remove_master_device(&mdev->bus_master);
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clk_disable_unprepare(mdev->clk);
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}
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static const struct of_device_id mxc_w1_dt_ids[] = {
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{ .compatible = "fsl,imx21-owire" },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, mxc_w1_dt_ids);
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static struct platform_driver mxc_w1_driver = {
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.driver = {
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.name = "mxc_w1",
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.of_match_table = mxc_w1_dt_ids,
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},
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.probe = mxc_w1_probe,
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.remove_new = mxc_w1_remove,
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};
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module_platform_driver(mxc_w1_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Freescale Semiconductors Inc");
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MODULE_DESCRIPTION("Driver for One-Wire on MXC");
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