w1: add 1-wire master driver for IP block found in SGI ASICs

Starting with SGI Origin machines nearly every new SGI ASIC contains
an 1-Wire master. They are used for attaching One-Wire prom devices,
which contain information about part numbers, revision numbers,
serial number etc. and MAC addresses for ethernet interfaces.
This patch adds a master driver to support this IP block.
It also adds an extra field dev_id to struct w1_bus_master, which
could be in used in slave drivers for creating unique device names.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Link: https://lore.kernel.org/r/20190831082623.15627-2-tbogendoerfer@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/w1/masters/Kconfig b/drivers/w1/masters/Kconfig
index 7ae2605..24b9a8e 100644 (file)
--- a/drivers/w1/masters/Kconfig
+++ b/drivers/w1/masters/Kconfig
@@ -65,5 +65,14 @@ config HDQ_MASTER_OMAP
          Say Y here if you want support for the 1-wire or HDQ Interface
          on an OMAP processor.
 
+config W1_MASTER_SGI
+       tristate "SGI ASIC driver"
+       help
+         Say Y here if you want support for your 1-wire devices using
+         SGI ASIC 1-Wire interface
+
+         This support is also available as a module.  If so, the module
+         will be called sgi_w1.
+
 endmenu
 

diff --git a/drivers/w1/masters/Makefile b/drivers/w1/masters/Makefile
index 18954ca..dae629b 100644 (file)
--- a/drivers/w1/masters/Makefile
+++ b/drivers/w1/masters/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_W1_MASTER_MXC)           += mxc_w1.o
 obj-$(CONFIG_W1_MASTER_DS1WM)          += ds1wm.o
 obj-$(CONFIG_W1_MASTER_GPIO)           += w1-gpio.o
 obj-$(CONFIG_HDQ_MASTER_OMAP)          += omap_hdq.o
+obj-$(CONFIG_W1_MASTER_SGI)            += sgi_w1.o

diff --git a/drivers/w1/masters/sgi_w1.c b/drivers/w1/masters/sgi_w1.c
new file mode 100644 (file)
index 0000000..1b2d96b
--- /dev/null
+++ b/drivers/w1/masters/sgi_w1.c
@@ -0,0 +1,130 @@
+// 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");

diff --git a/include/linux/platform_data/sgi-w1.h b/include/linux/platform_data/sgi-w1.h
new file mode 100644 (file)
index 0000000..e28c8a9
--- /dev/null
+++ b/include/linux/platform_data/sgi-w1.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * SGI One-Wire (W1) IP
+ */
+
+#ifndef PLATFORM_DATA_SGI_W1_H
+#define PLATFORM_DATA_SGI_W1_H
+
+struct sgi_w1_platform_data {
+       char dev_id[64];
+};
+
+#endif /* PLATFORM_DATA_SGI_W1_H */

diff --git a/include/linux/w1.h b/include/linux/w1.h
index e0b5156..7da0c75 100644 (file)
--- a/include/linux/w1.h
+++ b/include/linux/w1.h
@@ -118,6 +118,9 @@ typedef void (*w1_slave_found_callback)(struct w1_master *, u64);
  * w1_master* is passed to the slave found callback.
  * u8 is search_type, W1_SEARCH or W1_ALARM_SEARCH
  *
+ * @dev_id: Optional device id string, which w1 slaves could use for
+ * creating names, which then give a connection to the w1 master
+ *
  * Note: read_bit and write_bit are very low level functions and should only
  * be used with hardware that doesn't really support 1-wire operations,
  * like a parallel/serial port.
@@ -150,6 +153,8 @@ struct w1_bus_master {
 
        void            (*search)(void *, struct w1_master *,
                u8, w1_slave_found_callback);
+
+       char            *dev_id;
 };
 
 /**