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// SPDX-License-Identifier: GPL-2.0
/*
* sgi_w1.c - w1 master driver for one wire support in SGI ASICs
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/platform_data/sgi-w1.h>
#include <linux/w1.h>
#define MCR_RD_DATA BIT(0)
#define MCR_DONE BIT(1)
#define MCR_PACK(pulse, sample) (((pulse) << 10) | ((sample) << 2))
struct sgi_w1_device {
u32 __iomem *mcr;
struct w1_bus_master bus_master;
char dev_id[64];
};
static u8 sgi_w1_wait(u32 __iomem *mcr)
{
u32 mcr_val;
do {
mcr_val = readl(mcr);
} while (!(mcr_val & MCR_DONE));
return (mcr_val & MCR_RD_DATA) ? 1 : 0;
}
/*
* this is the low level routine to
* reset the device on the One Wire interface
* on the hardware
*/
static u8 sgi_w1_reset_bus(void *data)
{
struct sgi_w1_device *dev = data;
u8 ret;
writel(MCR_PACK(520, 65), dev->mcr);
ret = sgi_w1_wait(dev->mcr);
udelay(500); /* recovery time */
return ret;
}
/*
* this is the low level routine to read/write a bit on the One Wire
* interface on the hardware. It does write 0 if parameter bit is set
* to 0, otherwise a write 1/read.
*/
static u8 sgi_w1_touch_bit(void *data, u8 bit)
{
struct sgi_w1_device *dev = data;
u8 ret;
if (bit)
writel(MCR_PACK(6, 13), dev->mcr);
else
writel(MCR_PACK(80, 30), dev->mcr);
ret = sgi_w1_wait(dev->mcr);
if (bit)
udelay(100); /* recovery */
return ret;
}
static int sgi_w1_probe(struct platform_device *pdev)
{
struct sgi_w1_device *sdev;
struct sgi_w1_platform_data *pdata;
struct resource *res;
sdev = devm_kzalloc(&pdev->dev, sizeof(struct sgi_w1_device),
GFP_KERNEL);
if (!sdev)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
sdev->mcr = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(sdev->mcr))
return PTR_ERR(sdev->mcr);
sdev->bus_master.data = sdev;
sdev->bus_master.reset_bus = sgi_w1_reset_bus;
sdev->bus_master.touch_bit = sgi_w1_touch_bit;
pdata = dev_get_platdata(&pdev->dev);
if (pdata) {
strlcpy(sdev->dev_id, pdata->dev_id, sizeof(sdev->dev_id));
sdev->bus_master.dev_id = sdev->dev_id;
}
platform_set_drvdata(pdev, sdev);
return w1_add_master_device(&sdev->bus_master);
}
/*
* disassociate the w1 device from the driver
*/
static int sgi_w1_remove(struct platform_device *pdev)
{
struct sgi_w1_device *sdev = platform_get_drvdata(pdev);
w1_remove_master_device(&sdev->bus_master);
return 0;
}
static struct platform_driver sgi_w1_driver = {
.driver = {
.name = "sgi_w1",
},
.probe = sgi_w1_probe,
.remove = sgi_w1_remove,
};
module_platform_driver(sgi_w1_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Thomas Bogendoerfer");
MODULE_DESCRIPTION("Driver for One-Wire IP in SGI ASICs");
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