129 lines
2.7 KiB
C
129 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* sgi_w1.c - w1 master driver for one wire support in SGI ASICs
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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/jiffies.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/platform_data/sgi-w1.h>
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#include <linux/w1.h>
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#define MCR_RD_DATA BIT(0)
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#define MCR_DONE BIT(1)
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#define MCR_PACK(pulse, sample) (((pulse) << 10) | ((sample) << 2))
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struct sgi_w1_device {
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u32 __iomem *mcr;
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struct w1_bus_master bus_master;
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char dev_id[64];
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};
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static u8 sgi_w1_wait(u32 __iomem *mcr)
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{
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u32 mcr_val;
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do {
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mcr_val = readl(mcr);
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} while (!(mcr_val & MCR_DONE));
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return (mcr_val & MCR_RD_DATA) ? 1 : 0;
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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 sgi_w1_reset_bus(void *data)
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{
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struct sgi_w1_device *dev = data;
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u8 ret;
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writel(MCR_PACK(520, 65), dev->mcr);
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ret = sgi_w1_wait(dev->mcr);
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udelay(500); /* recovery time */
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return ret;
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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 sgi_w1_touch_bit(void *data, u8 bit)
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{
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struct sgi_w1_device *dev = data;
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u8 ret;
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if (bit)
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writel(MCR_PACK(6, 13), dev->mcr);
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else
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writel(MCR_PACK(80, 30), dev->mcr);
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ret = sgi_w1_wait(dev->mcr);
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if (bit)
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udelay(100); /* recovery */
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return ret;
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}
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static int sgi_w1_probe(struct platform_device *pdev)
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{
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struct sgi_w1_device *sdev;
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struct sgi_w1_platform_data *pdata;
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sdev = devm_kzalloc(&pdev->dev, sizeof(struct sgi_w1_device),
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GFP_KERNEL);
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if (!sdev)
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return -ENOMEM;
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sdev->mcr = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(sdev->mcr))
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return PTR_ERR(sdev->mcr);
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sdev->bus_master.data = sdev;
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sdev->bus_master.reset_bus = sgi_w1_reset_bus;
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sdev->bus_master.touch_bit = sgi_w1_touch_bit;
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pdata = dev_get_platdata(&pdev->dev);
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if (pdata) {
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strlcpy(sdev->dev_id, pdata->dev_id, sizeof(sdev->dev_id));
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sdev->bus_master.dev_id = sdev->dev_id;
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}
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platform_set_drvdata(pdev, sdev);
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return w1_add_master_device(&sdev->bus_master);
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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 int sgi_w1_remove(struct platform_device *pdev)
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{
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struct sgi_w1_device *sdev = platform_get_drvdata(pdev);
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w1_remove_master_device(&sdev->bus_master);
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return 0;
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}
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static struct platform_driver sgi_w1_driver = {
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.driver = {
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.name = "sgi_w1",
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},
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.probe = sgi_w1_probe,
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.remove = sgi_w1_remove,
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};
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module_platform_driver(sgi_w1_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Thomas Bogendoerfer");
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MODULE_DESCRIPTION("Driver for One-Wire IP in SGI ASICs");
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