Re: Finding 'orphaned' i2c drivers

Jon Smirl
2009-02-23T14:38:45Z

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On Mon, Feb 23, 2009 at 6:00 AM, Daniel Mack <daniel-rDUAYElUppE@public.gmane.org> wrote:
> Hi,
>
> what's the suggested way of implementing an i2c drver which does not
> have any other interfaces to the outside world than just the i2c device
> it is communicating with? More specifically, I implemented a driver for a
> Maxim clock generator and would like to use a proprietary interface with
> it from a alsa-soc module. I just can't find a sane way to access the
> driver's instance from there. It does exist somewhere in the linux
> device tree, but is there a simple function that iterates over it and
> returns it to me by name? Reading include/linux/device.h didn't point me
> to anything that could fit.

The max9485? Which codec are you using it with? I tried submitting the
attached driver for the chip but Jean said it was too simple of a
driver.

I use it like this:

static int dspeak01_fabric_hw_params(struct snd_pcm_substream
*substream, struct snd_pcm_hw_params *params)
{
uint rate, select;
int ret;
struct snd_soc_pcm_runtime *rtd = substream->private_data;
struct snd_soc_dai *cpu_dai = rtd->dai->cpu_dai;

printk("dspeak01_fabric_hw_params\n");

switch (params_rate(params)) {
case 11025:
case 22050:
case 44100:
case 88200:
case 176400:
rate = 22579200;
select = MAX9485_225792;
break;
default:
rate = 24576000;
select = MAX9485_245760;
break;
}
max9485_set(fabric.clock, select | MAX9485_CLK_OUT_2);

ret = cpu_dai->ops.set_sysclk(cpu_dai, MPC52xx_CLK_CELLSLAVE, rate,
SND_SOC_CLOCK_OUT);
if (ret < 0)
return ret;

return 0;
}

>
> Excuse me this is a stupid question, but I can't find any useful
> information about that anywhere.
>
> Thanks,
> Daniel
>
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--
Jon Smirl
jonsmirl-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

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i2c driver for Maxim max9485 audio clock generator chip

From: Jon Smirl <jonsmirl@gmail.com>

i2c driver for Maxim max9485 audio clock generator chip

Signed-off-by: Jon Smirl <jonsmirl@gmail.com>
---
drivers/misc/Kconfig | 9 ++++
drivers/misc/Makefile | 2 +
drivers/misc/max9485.c | 105 +++++++++++++++++++++++++++++++++++++++++++
include/linux/i2c/max9485.h | 39 ++++++++++++++++
4 files changed, 155 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/max9485.c
create mode 100644 include/linux/i2c/max9485.h

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index c64e679..320f359 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -150,6 +150,15 @@ config ATMEL_SSC

If unsure, say N.

+config MAX9485
+ tristate "Maxim MAX9485 Programmable Audio Clock Generator"
+ help
+ If you say yes here you get support for Maxim MAX9485
+ Programmable Audio Clock Generator.
+
+ This driver can also be built as a module. If so, the module
+ will be called max9485.
+
config ENCLOSURE_SERVICES
tristate "Enclosure Services"
default n
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index bc11998..7161709 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -13,6 +13,8 @@ obj-$(CONFIG_TIFM_CORE) += tifm_core.o
obj-$(CONFIG_TIFM_7XX1) += tifm_7xx1.o
obj-$(CONFIG_PHANTOM) += phantom.o
obj-$(CONFIG_SGI_IOC4) += ioc4.o
+obj-$(CONFIG_EEPROM_93CX6) += eeprom_93cx6.o
+obj-$(CONFIG_MAX9485) += max9485.o
obj-$(CONFIG_ENCLOSURE_SERVICES) += enclosure.o
obj-$(CONFIG_KGDB_TESTS) += kgdbts.o
obj-$(CONFIG_SGI_XP) += sgi-xp/
diff --git a/drivers/misc/max9485.c b/drivers/misc/max9485.c
new file mode 100644
index 0000000..c1316f2
--- /dev/null
+++ b/drivers/misc/max9485.c
@@ -0,0 +1,105 @@
+/*
+ * Maxim max9485 Programmable Audio Clock Generator driver
+ *
+ * Written by: Jon Smirl <jonsmirl@gmail.com>
+ *
+ * Copyright (C) 2008 Digispeaker.com
+ * Copyright (C) 2008 Jon Smirl <jonsmirl@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * This device is usually under the control of ALSA and should not be changed
+ * from userspace. The main purpose of this driver is to locate the i2c address
+ * of where the chip is located.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/sysfs.h>
+#include <linux/i2c/max9485.h>
+
+int max9485_set(struct i2c_client *max9485, u8 value)
+{
+ return i2c_smbus_write_byte(max9485, value);
+}
+EXPORT_SYMBOL_GPL(max9485_set);
+
+/*
+ * Display the only register
+ */
+static ssize_t max9485_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ int rc;
+
+ rc = i2c_smbus_read_byte(client);
+ if (rc < 0)
+ return rc;
+
+ return sprintf(buf, "%s%s%s%s%s%s",
+ (rc & MAX9485_MCLK ? "MCLK+" : ""),
+ (rc & MAX9485_CLK_OUT_2 ? "CLK2+" : ""),
+ (rc & MAX9485_CLK_OUT_2 ? "CLK1+" : ""),
+ (rc & MAX9485_DOUBLED ? "DOUBLED+" : ""),
+ (rc & MAX9485_SCALE_768 ? "768x+" : (rc & MAX9485_SCALE_384 ? "384x+" : "256x+")),
+ ((rc & 3) == MAX9485_FREQUENCY_48 ? "48Khz" :
+ ((rc & 3) == MAX9485_FREQUENCY_441 ? "44.1Khz" :
+ ((rc & 3) == MAX9485_FREQUENCY_32 ? "32Khz" : "12Khz"))));
+}
+static DEVICE_ATTR(max9485, S_IRUGO, max9485_show, NULL);
+
+/*
+ * Called when a max9485 device is matched with this driver
+ */
+static int max9485_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE)) {
+ dev_err(&client->dev, "i2c bus does not support the max9485\n");
+ return -ENODEV;
+ }
+ return sysfs_create_file(&client->dev.kobj, &dev_attr_max9485.attr);
+}
+
+static int max9485_remove(struct i2c_client *client)
+{
+ sysfs_remove_file(&client->dev.kobj, &dev_attr_max9485.attr);
+ return 0;
+}
+
+static const struct i2c_device_id max9485_id[] = {
+ { "max9485", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, max9485_id);
+
+static struct i2c_driver max9485_driver = {
+ .driver = {
+ .name = "max9485",
+ },
+ .probe = max9485_probe,
+ .remove = max9485_remove,
+ .id_table = max9485_id,
+};
+
+static int __init max9485_init(void)
+{
+ return i2c_add_driver(&max9485_driver);
+}
+
+static void __exit max9485_exit(void)
+{
+ i2c_del_driver(&max9485_driver);
+}
+
+MODULE_AUTHOR("Jon Smirl <jonsmirl@gmail.com");
+MODULE_DESCRIPTION("Maxim MAX9485 Programmable Audio Clock Generator driver");
+MODULE_LICENSE("GPL");
+
+module_init(max9485_init);
+module_exit(max9485_exit);
diff --git a/include/linux/i2c/max9485.h b/include/linux/i2c/max9485.h
new file mode 100644
index 0000000..81543bb
--- /dev/null
+++ b/include/linux/i2c/max9485.h
@@ -0,0 +1,39 @@
+/*
+ * Maxim max9485 Programmable Audio Clock Generator driver
+ *
+ * Written by: Jon Smirl <jonsmirl@gmail.com>
+ *
+ * Copyright (C) 2008 Digispeaker.com
+ * Copyright (C) 2008 Jon Smirl <jonsmirl@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __LINUX_I2C_MAX9485_H
+#define __LINUX_I2C_MAX9485_H
+
+struct i2c_client;
+
+/* Defines for Maxim MAX9485 Audio Clock Generator */
+
+#define MAX9485_MCLK (1 << 7)
+#define MAX9485_CLK_OUT_2 (1 << 6)
+#define MAX9485_CLK_OUT_1 (1 << 5)
+#define MAX9485_DOUBLED (1 << 4)
+#define MAX9485_SCALE_256 (0 << 2)
+#define MAX9485_SCALE_384 (1 << 2)
+#define MAX9485_SCALE_768 (2 << 2)
+#define MAX9485_FREQUENCY_12 0
+#define MAX9485_FREQUENCY_32 1
+#define MAX9485_FREQUENCY_441 2
+#define MAX9485_FREQUENCY_48 3
+
+/* Combinations that minimize jitter */
+#define MAX9485_245760 (MAX9485_SCALE_256 | MAX9485_FREQUENCY_48 | MAX9485_DOUBLED)
+#define MAX9485_225792 (MAX9485_SCALE_256 | MAX9485_FREQUENCY_441 | MAX9485_DOUBLED)
+
+int max9485_set(struct i2c_client *max9485, u8 value);
+
+#endif /* __LINUX_I2C_MAX9485_H */