drivers/i2c/busses/i2c-viai2c-wmt.c

Source file repositories/reference/linux-study-clean/drivers/i2c/busses/i2c-viai2c-wmt.c

File Facts

System
Linux kernel
Corpus path
drivers/i2c/busses/i2c-viai2c-wmt.c
Extension
.c
Size
4411 bytes
Lines
179
Domain
Driver Families
Bucket
drivers/i2c
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Wondermedia I2C Controller Driver
 *
 *  Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
 *
 *  Derived from GPLv2+ licensed source:
 *  - Copyright (C) 2008 WonderMedia Technologies, Inc.
 */

#include <linux/clk.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include "i2c-viai2c-common.h"

#define REG_SLAVE_CR	0x10
#define REG_SLAVE_SR	0x12
#define REG_SLAVE_ISR	0x14
#define REG_SLAVE_IMR	0x16
#define REG_SLAVE_DR	0x18
#define REG_SLAVE_TR	0x1A

/* REG_TR */
#define SCL_TIMEOUT(x)		(((x) & 0xFF) << 8)
#define TR_STD			0x0064
#define TR_HS			0x0019

/* REG_MCR */
#define MCR_APB_96M		7
#define MCR_APB_166M		12

static u32 wmt_i2c_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
}

static const struct i2c_algorithm wmt_i2c_algo = {
	.xfer = viai2c_xfer,
	.functionality = wmt_i2c_func,
};

static int wmt_i2c_reset_hardware(struct viai2c *i2c)
{
	int err;

	err = clk_prepare_enable(i2c->clk);
	if (err)
		return dev_err_probe(i2c->dev, err, "failed to enable clock\n");

	err = clk_set_rate(i2c->clk, 20000000);
	if (err) {
		clk_disable_unprepare(i2c->clk);
		return dev_err_probe(i2c->dev, err, "failed to set clock = 20Mhz\n");
	}

	writew(0, i2c->base + VIAI2C_REG_CR);
	writew(MCR_APB_166M, i2c->base + VIAI2C_REG_MCR);
	writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
	writew(VIAI2C_IMR_ENABLE_ALL, i2c->base + VIAI2C_REG_IMR);
	writew(VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR);
	readw(i2c->base + VIAI2C_REG_CSR);		/* read clear */
	writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);

	if (i2c->tcr == VIAI2C_TCR_FAST)
		writew(SCL_TIMEOUT(128) | TR_HS, i2c->base + VIAI2C_REG_TR);
	else
		writew(SCL_TIMEOUT(128) | TR_STD, i2c->base + VIAI2C_REG_TR);

	return 0;
}

static irqreturn_t wmt_i2c_isr(int irq, void *data)
{
	struct viai2c *i2c = data;
	u8 status;

	/* save the status and write-clear it */
	status = readw(i2c->base + VIAI2C_REG_ISR);
	writew(status, i2c->base + VIAI2C_REG_ISR);

	i2c->ret = 0;
	if (status & VIAI2C_ISR_NACK_ADDR)
		i2c->ret = -EIO;

	if (status & VIAI2C_ISR_SCL_TIMEOUT)
		i2c->ret = -ETIMEDOUT;

	if (!i2c->ret)
		i2c->ret = viai2c_irq_xfer(i2c);

Annotation

Implementation Notes