// SPDX-License-Identifier: GPL-2.0
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/*
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* i2c.c - Hardware Dependent Module for I2C Interface
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*
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* Copyright (C) 2013-2015, Microchip Technology Germany II GmbH & Co. KG
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/interrupt.h>
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#include <linux/err.h>
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#include <linux/most.h>
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enum { CH_RX, CH_TX, NUM_CHANNELS };
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#define MAX_BUFFERS_CONTROL 32
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#define MAX_BUF_SIZE_CONTROL 256
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/**
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* list_first_mbo - get the first mbo from a list
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* @ptr: the list head to take the mbo from.
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*/
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#define list_first_mbo(ptr) \
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list_first_entry(ptr, struct mbo, list)
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static unsigned int polling_rate;
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module_param(polling_rate, uint, 0644);
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MODULE_PARM_DESC(polling_rate, "Polling rate [Hz]. Default = 0 (use IRQ)");
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struct hdm_i2c {
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struct most_interface most_iface;
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struct most_channel_capability capabilities[NUM_CHANNELS];
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struct i2c_client *client;
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struct rx {
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struct delayed_work dwork;
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struct list_head list;
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bool int_disabled;
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unsigned int delay;
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} rx;
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char name[64];
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};
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#define to_hdm(iface) container_of(iface, struct hdm_i2c, most_iface)
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static irqreturn_t most_irq_handler(int, void *);
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static void pending_rx_work(struct work_struct *);
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/**
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* configure_channel - called from MOST core to configure a channel
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* @iface: interface the channel belongs to
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* @channel: channel to be configured
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* @channel_config: structure that holds the configuration information
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*
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* Return 0 on success, negative on failure.
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*
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* Receives configuration information from MOST core and initialize the
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* corresponding channel.
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*/
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static int configure_channel(struct most_interface *most_iface,
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int ch_idx,
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struct most_channel_config *channel_config)
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{
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int ret;
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struct hdm_i2c *dev = to_hdm(most_iface);
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unsigned int delay, pr;
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BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
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if (channel_config->data_type != MOST_CH_CONTROL) {
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pr_err("bad data type for channel %d\n", ch_idx);
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return -EPERM;
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}
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if (channel_config->direction != dev->capabilities[ch_idx].direction) {
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pr_err("bad direction for channel %d\n", ch_idx);
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return -EPERM;
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}
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if (channel_config->direction == MOST_CH_RX) {
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if (!polling_rate) {
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if (dev->client->irq <= 0) {
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pr_err("bad irq: %d\n", dev->client->irq);
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return -ENOENT;
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}
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dev->rx.int_disabled = false;
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ret = request_irq(dev->client->irq, most_irq_handler, 0,
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dev->client->name, dev);
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if (ret) {
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pr_err("request_irq(%d) failed: %d\n",
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dev->client->irq, ret);
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return ret;
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}
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} else {
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delay = msecs_to_jiffies(MSEC_PER_SEC / polling_rate);
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dev->rx.delay = delay ? delay : 1;
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pr = MSEC_PER_SEC / jiffies_to_msecs(dev->rx.delay);
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pr_info("polling rate is %u Hz\n", pr);
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}
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}
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return 0;
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}
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/**
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* enqueue - called from MOST core to enqueue a buffer for data transfer
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* @iface: intended interface
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* @channel: ID of the channel the buffer is intended for
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* @mbo: pointer to the buffer object
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*
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* Return 0 on success, negative on failure.
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*
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* Transmit the data over I2C if it is a "write" request or push the buffer into
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* list if it is an "read" request
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*/
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static int enqueue(struct most_interface *most_iface,
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int ch_idx, struct mbo *mbo)
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{
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struct hdm_i2c *dev = to_hdm(most_iface);
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int ret;
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BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
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if (ch_idx == CH_RX) {
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/* RX */
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if (!polling_rate)
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disable_irq(dev->client->irq);
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cancel_delayed_work_sync(&dev->rx.dwork);
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list_add_tail(&mbo->list, &dev->rx.list);
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if (dev->rx.int_disabled || polling_rate)
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pending_rx_work(&dev->rx.dwork.work);
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if (!polling_rate)
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enable_irq(dev->client->irq);
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} else {
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/* TX */
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ret = i2c_master_send(dev->client, mbo->virt_address,
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mbo->buffer_length);
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if (ret <= 0) {
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mbo->processed_length = 0;
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mbo->status = MBO_E_INVAL;
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} else {
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mbo->processed_length = mbo->buffer_length;
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mbo->status = MBO_SUCCESS;
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}
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mbo->complete(mbo);
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}
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return 0;
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}
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/**
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* poison_channel - called from MOST core to poison buffers of a channel
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* @iface: pointer to the interface the channel to be poisoned belongs to
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* @channel_id: corresponding channel ID
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*
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* Return 0 on success, negative on failure.
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*
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* If channel direction is RX, complete the buffers in list with
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* status MBO_E_CLOSE
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*/
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static int poison_channel(struct most_interface *most_iface,
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int ch_idx)
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{
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struct hdm_i2c *dev = to_hdm(most_iface);
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struct mbo *mbo;
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BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
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if (ch_idx == CH_RX) {
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if (!polling_rate)
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free_irq(dev->client->irq, dev);
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cancel_delayed_work_sync(&dev->rx.dwork);
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while (!list_empty(&dev->rx.list)) {
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mbo = list_first_mbo(&dev->rx.list);
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list_del(&mbo->list);
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mbo->processed_length = 0;
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mbo->status = MBO_E_CLOSE;
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mbo->complete(mbo);
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}
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}
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return 0;
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}
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static void do_rx_work(struct hdm_i2c *dev)
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{
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struct mbo *mbo;
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unsigned char msg[MAX_BUF_SIZE_CONTROL];
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int ret;
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u16 pml, data_size;
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/* Read PML (2 bytes) */
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ret = i2c_master_recv(dev->client, msg, 2);
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if (ret <= 0) {
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pr_err("Failed to receive PML\n");
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return;
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}
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pml = (msg[0] << 8) | msg[1];
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if (!pml)
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return;
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data_size = pml + 2;
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/* Read the whole message, including PML */
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ret = i2c_master_recv(dev->client, msg, data_size);
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if (ret <= 0) {
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pr_err("Failed to receive a Port Message\n");
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return;
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}
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mbo = list_first_mbo(&dev->rx.list);
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list_del(&mbo->list);
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mbo->processed_length = min(data_size, mbo->buffer_length);
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memcpy(mbo->virt_address, msg, mbo->processed_length);
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mbo->status = MBO_SUCCESS;
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mbo->complete(mbo);
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}
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/**
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* pending_rx_work - Read pending messages through I2C
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* @work: definition of this work item
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*
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* Invoked by the Interrupt Service Routine, most_irq_handler()
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*/
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static void pending_rx_work(struct work_struct *work)
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{
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struct hdm_i2c *dev = container_of(work, struct hdm_i2c, rx.dwork.work);
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if (list_empty(&dev->rx.list))
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return;
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do_rx_work(dev);
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if (polling_rate) {
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schedule_delayed_work(&dev->rx.dwork, dev->rx.delay);
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} else {
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dev->rx.int_disabled = false;
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enable_irq(dev->client->irq);
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}
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}
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/*
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* most_irq_handler - Interrupt Service Routine
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* @irq: irq number
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* @_dev: private data
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*
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* Schedules a delayed work
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*
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* By default the interrupt line behavior is Active Low. Once an interrupt is
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* generated by the device, until driver clears the interrupt (by reading
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* the PMP message), device keeps the interrupt line in low state. Since i2c
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* read is done in work queue, the interrupt line must be disabled temporarily
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* to avoid ISR being called repeatedly. Re-enable the interrupt in workqueue,
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* after reading the message.
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*
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* Note: If we use the interrupt line in Falling edge mode, there is a
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* possibility to miss interrupts when ISR is getting executed.
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*
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*/
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static irqreturn_t most_irq_handler(int irq, void *_dev)
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{
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struct hdm_i2c *dev = _dev;
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disable_irq_nosync(irq);
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dev->rx.int_disabled = true;
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schedule_delayed_work(&dev->rx.dwork, 0);
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return IRQ_HANDLED;
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}
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/*
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* i2c_probe - i2c probe handler
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* @client: i2c client device structure
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* @id: i2c client device id
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*
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* Return 0 on success, negative on failure.
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*
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* Register the i2c client device as a MOST interface
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*/
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static int i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
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{
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struct hdm_i2c *dev;
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int ret, i;
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dev = kzalloc(sizeof(*dev), GFP_KERNEL);
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if (!dev)
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return -ENOMEM;
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/* ID format: i2c-<bus>-<address> */
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snprintf(dev->name, sizeof(dev->name), "i2c-%d-%04x",
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client->adapter->nr, client->addr);
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for (i = 0; i < NUM_CHANNELS; i++) {
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dev->capabilities[i].data_type = MOST_CH_CONTROL;
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dev->capabilities[i].num_buffers_packet = MAX_BUFFERS_CONTROL;
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dev->capabilities[i].buffer_size_packet = MAX_BUF_SIZE_CONTROL;
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}
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dev->capabilities[CH_RX].direction = MOST_CH_RX;
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dev->capabilities[CH_RX].name_suffix = "rx";
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dev->capabilities[CH_TX].direction = MOST_CH_TX;
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dev->capabilities[CH_TX].name_suffix = "tx";
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dev->most_iface.interface = ITYPE_I2C;
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dev->most_iface.description = dev->name;
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dev->most_iface.num_channels = NUM_CHANNELS;
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dev->most_iface.channel_vector = dev->capabilities;
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dev->most_iface.configure = configure_channel;
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dev->most_iface.enqueue = enqueue;
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dev->most_iface.poison_channel = poison_channel;
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INIT_LIST_HEAD(&dev->rx.list);
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INIT_DELAYED_WORK(&dev->rx.dwork, pending_rx_work);
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dev->client = client;
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i2c_set_clientdata(client, dev);
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ret = most_register_interface(&dev->most_iface);
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if (ret) {
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pr_err("Failed to register i2c as a MOST interface\n");
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kfree(dev);
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return ret;
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}
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return 0;
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}
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/*
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* i2c_remove - i2c remove handler
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* @client: i2c client device structure
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*
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* Return 0 on success.
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*
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* Unregister the i2c client device as a MOST interface
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*/
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static int i2c_remove(struct i2c_client *client)
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{
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struct hdm_i2c *dev = i2c_get_clientdata(client);
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most_deregister_interface(&dev->most_iface);
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kfree(dev);
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return 0;
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}
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static const struct i2c_device_id i2c_id[] = {
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{ "most_i2c", 0 },
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{ }, /* Terminating entry */
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};
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MODULE_DEVICE_TABLE(i2c, i2c_id);
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static struct i2c_driver i2c_driver = {
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.driver = {
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.name = "hdm_i2c",
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},
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.probe = i2c_probe,
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.remove = i2c_remove,
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.id_table = i2c_id,
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};
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module_i2c_driver(i2c_driver);
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MODULE_AUTHOR("Andrey Shvetsov <andrey.shvetsov@k2l.de>");
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MODULE_DESCRIPTION("I2C Hardware Dependent Module");
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MODULE_LICENSE("GPL");
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