| // 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"); |