drivers/w1/masters/sgi_w1.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * sgi_w1.c - w1 master driver for one wire support in SGI ASICs
   4  */
   5
   6 #include <linux/clk.h>
   7 #include <linux/delay.h>
   8 #include <linux/io.h>
   9 #include <linux/jiffies.h>
  10 #include <linux/module.h>
  11 #include <linux/mod_devicetable.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/platform_data/sgi-w1.h>
  14
  15 #include <linux/w1.h>
  16
  17 #define MCR_RD_DATA     BIT(0)
  18 #define MCR_DONE        BIT(1)
  19
  20 #define MCR_PACK(pulse, sample) (((pulse) << 10) | ((sample) << 2))
  21
  22 struct sgi_w1_device {
  23         u32 __iomem *mcr;
  24         struct w1_bus_master bus_master;
  25         char dev_id[64];
  26 };
  27
  28 static u8 sgi_w1_wait(u32 __iomem *mcr)
  29 {
  30         u32 mcr_val;
  31
  32         do {
  33                 mcr_val = readl(mcr);
  34         } while (!(mcr_val & MCR_DONE));
  35
  36         return (mcr_val & MCR_RD_DATA) ? 1 : 0;
  37 }
  38
  39 /*
  40  * this is the low level routine to
  41  * reset the device on the One Wire interface
  42  * on the hardware
  43  */
  44 static u8 sgi_w1_reset_bus(void *data)
  45 {
  46         struct sgi_w1_device *dev = data;
  47         u8 ret;
  48
  49         writel(MCR_PACK(520, 65), dev->mcr);
  50         ret = sgi_w1_wait(dev->mcr);
  51         udelay(500); /* recovery time */
  52         return ret;
  53 }
  54
  55 /*
  56  * this is the low level routine to read/write a bit on the One Wire
  57  * interface on the hardware. It does write 0 if parameter bit is set
  58  * to 0, otherwise a write 1/read.
  59  */
  60 static u8 sgi_w1_touch_bit(void *data, u8 bit)
  61 {
  62         struct sgi_w1_device *dev = data;
  63         u8 ret;
  64
  65         if (bit)
  66                 writel(MCR_PACK(6, 13), dev->mcr);
  67         else
  68                 writel(MCR_PACK(80, 30), dev->mcr);
  69
  70         ret = sgi_w1_wait(dev->mcr);
  71         if (bit)
  72                 udelay(100); /* recovery */
  73         return ret;
  74 }
  75
  76 static int sgi_w1_probe(struct platform_device *pdev)
  77 {
  78         struct sgi_w1_device *sdev;
  79         struct sgi_w1_platform_data *pdata;
  80
  81         sdev = devm_kzalloc(&pdev->dev, sizeof(struct sgi_w1_device),
  82                             GFP_KERNEL);
  83         if (!sdev)
  84                 return -ENOMEM;
  85
  86         sdev->mcr = devm_platform_ioremap_resource(pdev, 0);
  87         if (IS_ERR(sdev->mcr))
  88                 return PTR_ERR(sdev->mcr);
  89
  90         sdev->bus_master.data = sdev;
  91         sdev->bus_master.reset_bus = sgi_w1_reset_bus;
  92         sdev->bus_master.touch_bit = sgi_w1_touch_bit;
  93
  94         pdata = dev_get_platdata(&pdev->dev);
  95         if (pdata) {
  96                 strscpy(sdev->dev_id, pdata->dev_id, sizeof(sdev->dev_id));
  97                 sdev->bus_master.dev_id = sdev->dev_id;
  98         }
  99
 100         platform_set_drvdata(pdev, sdev);
 101
 102         return w1_add_master_device(&sdev->bus_master);
 103 }
 104
 105 /*
 106  * disassociate the w1 device from the driver
 107  */
 108 static void sgi_w1_remove(struct platform_device *pdev)
 109 {
 110         struct sgi_w1_device *sdev = platform_get_drvdata(pdev);
 111
 112         w1_remove_master_device(&sdev->bus_master);
 113 }
 114
 115 static struct platform_driver sgi_w1_driver = {
 116         .driver = {
 117                 .name = "sgi_w1",
 118         },
 119         .probe = sgi_w1_probe,
 120         .remove = sgi_w1_remove,
 121 };
 122 module_platform_driver(sgi_w1_driver);
 123
 124 MODULE_LICENSE("GPL");
 125 MODULE_AUTHOR("Thomas Bogendoerfer");
 126 MODULE_DESCRIPTION("Driver for One-Wire IP in SGI ASICs");