[RFC 2/3] i2c: mux: demux-pinctrl: add driver
From: geert@linux-m68k.org (Geert Uytterhoeven)
Date: 2015-07-01 07:08:12
Also in:
linux-devicetree, linux-i2c, linux-sh
Hi Wolfram, On Tue, Jun 30, 2015 at 11:44 PM, Wolfram Sang [off-list ref] wrote:
quoted hunk
From: Wolfram Sang <wsa+renesas@sang-engineering.com> This driver allows an I2C bus to switch between multiple masters. This is not hot-switching because connected I2C slaves will be re-instantiated. It is meant to select the best I2C core at runtime once the task is known. Example: Prefer i2c-gpio over another I2C core because of HW errata affecting your use case. Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> --- .../devicetree/bindings/i2c/i2c-demux-pinctrl.txt | 44 ++++ drivers/i2c/muxes/Kconfig | 9 + drivers/i2c/muxes/Makefile | 2 + drivers/i2c/muxes/i2c-demux-pinctrl.c | 266 +++++++++++++++++++++ 4 files changed, 321 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt create mode 100644 drivers/i2c/muxes/i2c-demux-pinctrl.cdiff --git a/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt new file mode 100644 index 00000000000000..2211f6acbf8c0c --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
+Changing I2C controllers: + +The created mux-device will have a file "cur_master" in its sysfs-entry. Write +0 there for the first master listed in the "i2c-parent" property, 1 for the +second etc. Reading the file will give you a list with the active master +marked.
This paragraph doesn't belong in the DT binding doc, but somewhere under Documentation/i2c/
quoted hunk
diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c new file mode 100644 index 00000000000000..5444c65de76c55 --- /dev/null +++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c@@ -0,0 +1,266 @@ +/* + * Pinctrl based I2C DeMultiplexer V2 PROTOTYPE! + * + * Copyright (C) 2015 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com> + * Copyright (C) 2015 by Renesas Electronics Corporation + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; version 2 of the License. + * + * See the bindings doc for DTS setup. + */ + +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/of.h> +#include <linux/pinctrl/consumer.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/sysfs.h> + +struct i2c_demux_pinctrl_chan { + struct device_node *parent_np; + struct i2c_adapter *parent_adap; + struct of_changeset chgset; +}; + +struct i2c_demux_pinctrl_priv { + int cur_chan; + int num_chan;
unsigned int
+ struct device *dev;
+ const char *bus_name;
+ struct i2c_adapter cur_adap;
+ struct i2c_algorithm algo;
+ struct i2c_demux_pinctrl_chan chan[];
+};
+
+static struct property status_okay = { .name = "status", .length = 3, .value = "ok" };"okay" or "ok"?
+static ssize_t cur_master_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
+ int count = 0, i;unsigned int i
+ + for (i = 0; i < priv->num_chan; i++) + count += sprintf(buf + count, "%c %d - %s\n", + i == priv->cur_chan ? '*' : ' ', i, + priv->chan[i].parent_np->full_name); + //FIXME: Check count > PAGE_SIZE
Can you use seq_printf() for device attributes?
+
+ return count;
+}
+
+static ssize_t cur_master_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev);
+ unsigned long val;unsigned int
+ int ret; + + ret = kstrtoul(buf, 0, &val);
kstrtouint()
+ if (ret < 0) + return ret; + + if (val >= priv->num_chan) + return -EINVAL;
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds