i2c-viai2c-wmt.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *  Wondermedia I2C Controller Driver
  4 *
  5 *  Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>
  6 *
  7 *  Derived from GPLv2+ licensed source:
  8 *  - Copyright (C) 2008 WonderMedia Technologies, Inc.
  9 */
 10
 11#include <linux/clk.h>
 12#include <linux/of.h>
 13#include <linux/of_address.h>
 14#include "i2c-viai2c-common.h"
 15
 16#define REG_SLAVE_CR	0x10
 17#define REG_SLAVE_SR	0x12
 18#define REG_SLAVE_ISR	0x14
 19#define REG_SLAVE_IMR	0x16
 20#define REG_SLAVE_DR	0x18
 21#define REG_SLAVE_TR	0x1A
 22
 23/* REG_TR */
 24#define SCL_TIMEOUT(x)		(((x) & 0xFF) << 8)
 25#define TR_STD			0x0064
 26#define TR_HS			0x0019
 27
 28/* REG_MCR */
 29#define MCR_APB_96M		7
 30#define MCR_APB_166M		12
 31
 32static u32 wmt_i2c_func(struct i2c_adapter *adap)
 33{
 34	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
 35}
 36
 37static const struct i2c_algorithm wmt_i2c_algo = {
 38	.xfer = viai2c_xfer,
 39	.functionality = wmt_i2c_func,
 40};
 41
 42static int wmt_i2c_reset_hardware(struct viai2c *i2c)
 43{
 44	int err;
 45
 46	err = clk_prepare_enable(i2c->clk);
 47	if (err)
 48		return dev_err_probe(i2c->dev, err, "failed to enable clock\n");
 49
 50	err = clk_set_rate(i2c->clk, 20000000);
 51	if (err) {
 52		clk_disable_unprepare(i2c->clk);
 53		return dev_err_probe(i2c->dev, err, "failed to set clock = 20Mhz\n");
 54	}
 55
 56	writew(0, i2c->base + VIAI2C_REG_CR);
 57	writew(MCR_APB_166M, i2c->base + VIAI2C_REG_MCR);
 58	writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
 59	writew(VIAI2C_IMR_ENABLE_ALL, i2c->base + VIAI2C_REG_IMR);
 60	writew(VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR);
 61	readw(i2c->base + VIAI2C_REG_CSR);		/* read clear */
 62	writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
 63
 64	if (i2c->tcr == VIAI2C_TCR_FAST)
 65		writew(SCL_TIMEOUT(128) | TR_HS, i2c->base + VIAI2C_REG_TR);
 66	else
 67		writew(SCL_TIMEOUT(128) | TR_STD, i2c->base + VIAI2C_REG_TR);
 68
 69	return 0;
 70}
 71
 72static irqreturn_t wmt_i2c_isr(int irq, void *data)
 73{
 74	struct viai2c *i2c = data;
 75	u8 status;
 76
 77	/* save the status and write-clear it */
 78	status = readw(i2c->base + VIAI2C_REG_ISR);
 79	writew(status, i2c->base + VIAI2C_REG_ISR);
 80
 81	i2c->ret = 0;
 82	if (status & VIAI2C_ISR_NACK_ADDR)
 83		i2c->ret = -EIO;
 84
 85	if (status & VIAI2C_ISR_SCL_TIMEOUT)
 86		i2c->ret = -ETIMEDOUT;
 87
 88	if (!i2c->ret)
 89		i2c->ret = viai2c_irq_xfer(i2c);
 90
 91	/* All the data has been successfully transferred or error occurred */
 92	if (i2c->ret)
 93		complete(&i2c->complete);
 94
 95	return IRQ_HANDLED;
 96}
 97
 98static int wmt_i2c_probe(struct platform_device *pdev)
 99{
100	struct device_node *np = pdev->dev.of_node;
101	struct viai2c *i2c;
102	struct i2c_adapter *adap;
103	int err;
104	u32 clk_rate;
105
106	err = viai2c_init(pdev, &i2c, VIAI2C_PLAT_WMT);
107	if (err)
108		return err;
109
110	i2c->irq = platform_get_irq(pdev, 0);
111	if (i2c->irq < 0)
112		return i2c->irq;
113
114	err = devm_request_irq(&pdev->dev, i2c->irq, wmt_i2c_isr,
115			       0, pdev->name, i2c);
116	if (err)
117		return dev_err_probe(&pdev->dev, err,
118				"failed to request irq %i\n", i2c->irq);
119
120	i2c->clk = of_clk_get(np, 0);
121	if (IS_ERR(i2c->clk))
122		return dev_err_probe(&pdev->dev, PTR_ERR(i2c->clk),
123				     "unable to request clock\n");
124
125	err = of_property_read_u32(np, "clock-frequency", &clk_rate);
126	if (!err && clk_rate == I2C_MAX_FAST_MODE_FREQ)
127		i2c->tcr = VIAI2C_TCR_FAST;
128
129	adap = &i2c->adapter;
130	i2c_set_adapdata(adap, i2c);
131	strscpy(adap->name, "WMT I2C adapter", sizeof(adap->name));
132	adap->owner = THIS_MODULE;
133	adap->algo = &wmt_i2c_algo;
134	adap->dev.parent = &pdev->dev;
135	adap->dev.of_node = pdev->dev.of_node;
136
137	err = wmt_i2c_reset_hardware(i2c);
138	if (err)
139		return err;
140
141	err = i2c_add_adapter(adap);
142	if (err)
143		/* wmt_i2c_reset_hardware() enables i2c_dev->clk */
144		clk_disable_unprepare(i2c->clk);
145
146	return err;
147}
148
149static void wmt_i2c_remove(struct platform_device *pdev)
150{
151	struct viai2c *i2c = platform_get_drvdata(pdev);
152
153	/* Disable interrupts, clock and delete adapter */
154	writew(0, i2c->base + VIAI2C_REG_IMR);
155	clk_disable_unprepare(i2c->clk);
156	i2c_del_adapter(&i2c->adapter);
157}
158
159static const struct of_device_id wmt_i2c_dt_ids[] = {
160	{ .compatible = "wm,wm8505-i2c" },
161	{ /* Sentinel */ },
162};
163
164static struct platform_driver wmt_i2c_driver = {
165	.probe		= wmt_i2c_probe,
166	.remove		= wmt_i2c_remove,
167	.driver		= {
168		.name	= "wmt-i2c",
169		.of_match_table = wmt_i2c_dt_ids,
170	},
171};
172
173module_platform_driver(wmt_i2c_driver);
174
175MODULE_DESCRIPTION("Wondermedia I2C controller driver");
176MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
177MODULE_LICENSE("GPL");
178MODULE_DEVICE_TABLE(of, wmt_i2c_dt_ids);