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
22struct sgi_w1_device {
23 u32 __iomem *mcr;
24 struct w1_bus_master bus_master;
25 char dev_id[64];
26};
27
28static u8 sgi_w1_wait(u32 __iomem *mcr)
29{
30 u32 mcr_val;
31
32 do {
33 mcr_val = readl(addr: 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 */
44static 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), addr: dev->mcr);
50 ret = sgi_w1_wait(mcr: 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 */
60static 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), addr: dev->mcr);
67 else
68 writel(MCR_PACK(80, 30), addr: dev->mcr);
69
70 ret = sgi_w1_wait(mcr: dev->mcr);
71 if (bit)
72 udelay(100); /* recovery */
73 return ret;
74}
75
76static 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(dev: &pdev->dev, size: sizeof(struct sgi_w1_device),
82 GFP_KERNEL);
83 if (!sdev)
84 return -ENOMEM;
85
86 sdev->mcr = devm_platform_ioremap_resource(pdev, index: 0);
87 if (IS_ERR(ptr: sdev->mcr))
88 return PTR_ERR(ptr: 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(dev: &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, data: sdev);
101
102 return w1_add_master_device(master: &sdev->bus_master);
103}
104
105/*
106 * disassociate the w1 device from the driver
107 */
108static 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(master: &sdev->bus_master);
113}
114
115static struct platform_driver sgi_w1_driver = {
116 .driver = {
117 .name = "sgi_w1",
118 },
119 .probe = sgi_w1_probe,
120 .remove_new = sgi_w1_remove,
121};
122module_platform_driver(sgi_w1_driver);
123
124MODULE_LICENSE("GPL");
125MODULE_AUTHOR("Thomas Bogendoerfer");
126MODULE_DESCRIPTION("Driver for One-Wire IP in SGI ASICs");
127

source code of linux/drivers/w1/masters/sgi_w1.c