Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / gpio / gpio-max7301.c

diff --git a/kernel/drivers/gpio/gpio-max7301.c b/kernel/drivers/gpio/gpio-max7301.c
new file mode 100644 (file)
index 0000000..6e1c984
--- /dev/null
+++ b/kernel/drivers/gpio/gpio-max7301.c
@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2006 Juergen Beisert, Pengutronix
+ * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
+ * Copyright (C) 2009 Wolfram Sang, Pengutronix
+ *
+ * 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.
+ *
+ * Check max730x.c for further details.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/max7301.h>
+
+/* A write to the MAX7301 means one message with one transfer */
+static int max7301_spi_write(struct device *dev, unsigned int reg,
+                               unsigned int val)
+{
+       struct spi_device *spi = to_spi_device(dev);
+       u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);
+
+       return spi_write(spi, (const u8 *)&word, sizeof(word));
+}
+
+/* A read from the MAX7301 means two transfers; here, one message each */
+
+static int max7301_spi_read(struct device *dev, unsigned int reg)
+{
+       int ret;
+       u16 word;
+       struct spi_device *spi = to_spi_device(dev);
+
+       word = 0x8000 | (reg << 8);
+       ret = spi_write(spi, (const u8 *)&word, sizeof(word));
+       if (ret)
+               return ret;
+       /*
+        * This relies on the fact, that a transfer with NULL tx_buf shifts out
+        * zero bytes (=NOOP for MAX7301)
+        */
+       ret = spi_read(spi, (u8 *)&word, sizeof(word));
+       if (ret)
+               return ret;
+       return word & 0xff;
+}
+
+static int max7301_probe(struct spi_device *spi)
+{
+       struct max7301 *ts;
+       int ret;
+
+       /* bits_per_word cannot be configured in platform data */
+       spi->bits_per_word = 16;
+       ret = spi_setup(spi);
+       if (ret < 0)
+               return ret;
+
+       ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);
+       if (!ts)
+               return -ENOMEM;
+
+       ts->read = max7301_spi_read;
+       ts->write = max7301_spi_write;
+       ts->dev = &spi->dev;
+
+       ret = __max730x_probe(ts);
+       return ret;
+}
+
+static int max7301_remove(struct spi_device *spi)
+{
+       return __max730x_remove(&spi->dev);
+}
+
+static const struct spi_device_id max7301_id[] = {
+       { "max7301", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(spi, max7301_id);
+
+static struct spi_driver max7301_driver = {
+       .driver = {
+               .name = "max7301",
+               .owner = THIS_MODULE,
+       },
+       .probe = max7301_probe,
+       .remove = max7301_remove,
+       .id_table = max7301_id,
+};
+
+static int __init max7301_init(void)
+{
+       return spi_register_driver(&max7301_driver);
+}
+/* register after spi postcore initcall and before
+ * subsys initcalls that may rely on these GPIOs
+ */
+subsys_initcall(max7301_init);
+
+static void __exit max7301_exit(void)
+{
+       spi_unregister_driver(&max7301_driver);
+}
+module_exit(max7301_exit);
+
+MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MAX7301 GPIO-Expander");