linux/drivers/staging/most/i2c/i2c.c

// SPDX-License-Identifier: GPL-2.0
/*
 * i2c.c - Hardware Dependent Module for I2C Interface
 *
 * Copyright (C) 2013-2015, Microchip Technology Germany II GmbH & Co. KG
 */

#define pr_fmt(fmt) …

#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/most.h>

enum { … };

#define MAX_BUFFERS_CONTROL …
#define MAX_BUF_SIZE_CONTROL …

/**
 * list_first_mbo - get the first mbo from a list
 * @ptr:	the list head to take the mbo from.
 */
#define list_first_mbo(ptr) …

static unsigned int polling_rate;
module_param(polling_rate, uint, 0644);
MODULE_PARM_DESC(…) …;

struct hdm_i2c { … };

static inline struct hdm_i2c *to_hdm(struct most_interface *iface)
{ … }

static irqreturn_t most_irq_handler(int, void *);
static void pending_rx_work(struct work_struct *);

/**
 * configure_channel - called from MOST core to configure a channel
 * @most_iface: interface the channel belongs to
 * @ch_idx: channel to be configured
 * @channel_config: structure that holds the configuration information
 *
 * Return 0 on success, negative on failure.
 *
 * Receives configuration information from MOST core and initialize the
 * corresponding channel.
 */
static int configure_channel(struct most_interface *most_iface,
			     int ch_idx,
			     struct most_channel_config *channel_config)
{ … }

/**
 * enqueue - called from MOST core to enqueue a buffer for data transfer
 * @most_iface: intended interface
 * @ch_idx: ID of the channel the buffer is intended for
 * @mbo: pointer to the buffer object
 *
 * Return 0 on success, negative on failure.
 *
 * Transmit the data over I2C if it is a "write" request or push the buffer into
 * list if it is an "read" request
 */
static int enqueue(struct most_interface *most_iface,
		   int ch_idx, struct mbo *mbo)
{ … }

/**
 * poison_channel - called from MOST core to poison buffers of a channel
 * @most_iface: pointer to the interface the channel to be poisoned belongs to
 * @ch_idx: corresponding channel ID
 *
 * Return 0 on success, negative on failure.
 *
 * If channel direction is RX, complete the buffers in list with
 * status MBO_E_CLOSE
 */
static int poison_channel(struct most_interface *most_iface,
			  int ch_idx)
{ … }

static void do_rx_work(struct hdm_i2c *dev)
{ … }

/**
 * pending_rx_work - Read pending messages through I2C
 * @work: definition of this work item
 *
 * Invoked by the Interrupt Service Routine, most_irq_handler()
 */
static void pending_rx_work(struct work_struct *work)
{ … }

/*
 * most_irq_handler - Interrupt Service Routine
 * @irq: irq number
 * @_dev: private data
 *
 * Schedules a delayed work
 *
 * By default the interrupt line behavior is Active Low. Once an interrupt is
 * generated by the device, until driver clears the interrupt (by reading
 * the PMP message), device keeps the interrupt line in low state. Since i2c
 * read is done in work queue, the interrupt line must be disabled temporarily
 * to avoid ISR being called repeatedly. Re-enable the interrupt in workqueue,
 * after reading the message.
 *
 * Note: If we use the interrupt line in Falling edge mode, there is a
 * possibility to miss interrupts when ISR is getting executed.
 *
 */
static irqreturn_t most_irq_handler(int irq, void *_dev)
{ … }

/*
 * i2c_probe - i2c probe handler
 * @client: i2c client device structure
 * @id: i2c client device id
 *
 * Return 0 on success, negative on failure.
 *
 * Register the i2c client device as a MOST interface
 */
static int i2c_probe(struct i2c_client *client)
{ … }

/*
 * i2c_remove - i2c remove handler
 * @client: i2c client device structure
 *
 * Return 0 on success.
 *
 * Unregister the i2c client device as a MOST interface
 */
static void i2c_remove(struct i2c_client *client)
{ … }

static const struct i2c_device_id i2c_id[] = …;

MODULE_DEVICE_TABLE(i2c, i2c_id);

static struct i2c_driver i2c_driver = …;

module_i2c_driver(…) …;

MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;