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path: root/drivers/w1/masters/sgi_w1.c
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Diffstat (limited to 'drivers/w1/masters/sgi_w1.c')
-rw-r--r--drivers/w1/masters/sgi_w1.c128
1 files changed, 128 insertions, 0 deletions
diff --git a/drivers/w1/masters/sgi_w1.c b/drivers/w1/masters/sgi_w1.c
new file mode 100644
index 0000000000..d7fbc3c146
--- /dev/null
+++ b/drivers/w1/masters/sgi_w1.c
@@ -0,0 +1,128 @@
+// 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");