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128 lines
2.7 KiB
128 lines
2.7 KiB
// 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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