Fixed MTP to work with TWRP

Documentation/blackfin/00-INDEX

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+00-INDEX
+	- This file
+Makefile
+	- Makefile for gptimers example file.
+bfin-gpio-notes.txt
+	- Notes in developing/using bfin-gpio driver.
+bfin-spi-notes.txt
+	- Notes for using bfin spi bus driver.
+gptimers-example.c
+	- gptimers example

Documentation/blackfin/Makefile

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+ifneq ($(CONFIG_BLACKFIN),)
+obj-m := gptimers-example.o
+endif

Documentation/blackfin/bfin-gpio-notes.txt

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+/*
+ * File:         Documentation/blackfin/bfin-gpio-notes.txt
+ * Based on:
+ * Author:
+ *
+ * Created:      $Id: bfin-gpio-note.txt 2008-11-24 16:42 grafyang $
+ * Description:  This file contains the notes in developing/using bfin-gpio.
+ *
+ *
+ * Rev:
+ *
+ * Modified:
+ *               Copyright 2004-2008 Analog Devices Inc.
+ *
+ * Bugs:         Enter bugs at http://blackfin.uclinux.org/
+ *
+ */
+
+
+1. Blackfin GPIO introduction
+
+    There are many GPIO pins on Blackfin. Most of these pins are muxed to
+    multi-functions. They can be configured as peripheral, or just as GPIO,
+    configured to input with interrupt enabled, or output.
+
+    For detailed information, please see "arch/blackfin/kernel/bfin_gpio.c",
+    or the relevant HRM.
+
+
+2. Avoiding resource conflict
+
+    Followed function groups are used to avoiding resource conflict,
+    - Use the pin as peripheral,
+	int peripheral_request(unsigned short per, const char *label);
+	int peripheral_request_list(const unsigned short per[], const char *label);
+	void peripheral_free(unsigned short per);
+	void peripheral_free_list(const unsigned short per[]);
+    - Use the pin as GPIO,
+	int bfin_gpio_request(unsigned gpio, const char *label);
+	void bfin_gpio_free(unsigned gpio);
+    - Use the pin as GPIO interrupt,
+	int bfin_gpio_irq_request(unsigned gpio, const char *label);
+	void bfin_gpio_irq_free(unsigned gpio);
+
+    The request functions will record the function state for a certain pin,
+    the free functions will clear its function state.
+    Once a pin is requested, it can't be requested again before it is freed by
+    previous caller, otherwise kernel will dump stacks, and the request
+    function fail.
+    These functions are wrapped by other functions, most of the users need not
+    care.
+
+
+3. But there are some exceptions
+    - Kernel permit the identical GPIO be requested both as GPIO and GPIO
+    interrupt.
+    Some drivers, like gpio-keys, need this behavior. Kernel only print out
+    warning messages like,
+	bfin-gpio: GPIO 24 is already reserved by gpio-keys: BTN0, and you are
+configuring it as IRQ!
+
+        Note: Consider the case that, if there are two drivers need the
+	identical GPIO, one of them use it as GPIO, the other use it as
+	GPIO interrupt. This will really cause resource conflict. So if
+	there is any abnormal driver behavior, please check the bfin-gpio
+	warning messages.
+
+    - Kernel permit the identical GPIO be requested from the same driver twice.
+
+
+

Documentation/blackfin/bfin-spi-notes.txt

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+SPI Chip Select behavior:
+
+With the Blackfin on-chip SPI peripheral, there is some logic tied to the CPHA
+bit whether the Slave Select Line is controlled by hardware (CPHA=0) or
+controlled by software (CPHA=1). However, the Linux SPI bus driver assumes that
+the Slave Select is always under software control and being asserted during
+the entire SPI transfer. - And not just bits_per_word duration.
+
+In most cases you can utilize SPI MODE_3 instead of MODE_0 to work-around this
+behavior. If your SPI slave device in question requires SPI MODE_0 or MODE_2
+timing, you can utilize the GPIO controlled SPI Slave Select option instead.
+In this case, you should use GPIO based CS for all of your slaves and not just
+the ones using mode 0 or 2 in order to guarantee correct CS toggling behavior.
+
+You can even use the same pin whose peripheral role is a SSEL,
+but use it as a GPIO instead.

Documentation/blackfin/gptimers-example.c

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+/*
+ * Simple gptimers example
+ *	http://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:gptimers
+ *
+ * Copyright 2007-2009 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+
+#include <asm/gptimers.h>
+#include <asm/portmux.h>
+
+/* ... random driver includes ... */
+
+#define DRIVER_NAME "gptimer_example"
+
+struct gptimer_data {
+	uint32_t period, width;
+};
+static struct gptimer_data data;
+
+/* ... random driver state ... */
+
+static irqreturn_t gptimer_example_irq(int irq, void *dev_id)
+{
+	struct gptimer_data *data = dev_id;
+
+	/* make sure it was our timer which caused the interrupt */
+	if (!get_gptimer_intr(TIMER5_id))
+		return IRQ_NONE;
+
+	/* read the width/period values that were captured for the waveform */
+	data->width = get_gptimer_pwidth(TIMER5_id);
+	data->period = get_gptimer_period(TIMER5_id);
+
+	/* acknowledge the interrupt */
+	clear_gptimer_intr(TIMER5_id);
+
+	/* tell the upper layers we took care of things */
+	return IRQ_HANDLED;
+}
+
+/* ... random driver code ... */
+
+static int __init gptimer_example_init(void)
+{
+	int ret;
+
+	/* grab the peripheral pins */
+	ret = peripheral_request(P_TMR5, DRIVER_NAME);
+	if (ret) {
+		printk(KERN_NOTICE DRIVER_NAME ": peripheral request failed\n");
+		return ret;
+	}
+
+	/* grab the IRQ for the timer */
+	ret = request_irq(IRQ_TIMER5, gptimer_example_irq, IRQF_SHARED, DRIVER_NAME, &data);
+	if (ret) {
+		printk(KERN_NOTICE DRIVER_NAME ": IRQ request failed\n");
+		peripheral_free(P_TMR5);
+		return ret;
+	}
+
+	/* setup the timer and enable it */
+	set_gptimer_config(TIMER5_id, WDTH_CAP | PULSE_HI | PERIOD_CNT | IRQ_ENA);
+	enable_gptimers(TIMER5bit);
+
+	return 0;
+}
+module_init(gptimer_example_init);
+
+static void __exit gptimer_example_exit(void)
+{
+	disable_gptimers(TIMER5bit);
+	free_irq(IRQ_TIMER5, &data);
+	peripheral_free(P_TMR5);
+}
+module_exit(gptimer_example_exit);
+
+MODULE_LICENSE("BSD");