// 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; sdev = devm_kzalloc(&pdev->dev, sizeof(struct sgi_w1_device), GFP_KERNEL); if (!sdev) return -ENOMEM; sdev->mcr = devm_platform_ioremap_resource(pdev, 0); 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) { strscpy(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");