drivers/i2c/busses/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
  32 static u32 wmt_i2c_func(struct i2c_adapter *adap)
  33 {
  34         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
  35 }
  36
  37 static const struct i2c_algorithm wmt_i2c_algo = {
  38         .xfer = viai2c_xfer,
  39         .functionality = wmt_i2c_func,
  40 };
  41
  42 static int wmt_i2c_reset_hardware(struct viai2c *i2c)
  43 {
  44         int err;
  45
  46         err = clk_prepare_enable(i2c->clk);
  47         if (err) {
  48                 dev_err(i2c->dev, "failed to enable clock\n");
  49                 return err;
  50         }
  51
  52         err = clk_set_rate(i2c->clk, 20000000);
  53         if (err) {
  54                 dev_err(i2c->dev, "failed to set clock = 20Mhz\n");
  55                 clk_disable_unprepare(i2c->clk);
  56                 return err;
  57         }
  58
  59         writew(0, i2c->base + VIAI2C_REG_CR);
  60         writew(MCR_APB_166M, i2c->base + VIAI2C_REG_MCR);
  61         writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
  62         writew(VIAI2C_IMR_ENABLE_ALL, i2c->base + VIAI2C_REG_IMR);
  63         writew(VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR);
  64         readw(i2c->base + VIAI2C_REG_CSR);              /* read clear */
  65         writew(VIAI2C_ISR_MASK_ALL, i2c->base + VIAI2C_REG_ISR);
  66
  67         if (i2c->tcr == VIAI2C_TCR_FAST)
  68                 writew(SCL_TIMEOUT(128) | TR_HS, i2c->base + VIAI2C_REG_TR);
  69         else
  70                 writew(SCL_TIMEOUT(128) | TR_STD, i2c->base + VIAI2C_REG_TR);
  71
  72         return 0;
  73 }
  74
  75 static irqreturn_t wmt_i2c_isr(int irq, void *data)
  76 {
  77         struct viai2c *i2c = data;
  78         u8 status;
  79
  80         /* save the status and write-clear it */
  81         status = readw(i2c->base + VIAI2C_REG_ISR);
  82         writew(status, i2c->base + VIAI2C_REG_ISR);
  83
  84         i2c->ret = 0;
  85         if (status & VIAI2C_ISR_NACK_ADDR)
  86                 i2c->ret = -EIO;
  87
  88         if (status & VIAI2C_ISR_SCL_TIMEOUT)
  89                 i2c->ret = -ETIMEDOUT;
  90
  91         if (!i2c->ret)
  92                 i2c->ret = viai2c_irq_xfer(i2c);
  93
  94         /* All the data has been successfully transferred or error occurred */
  95         if (i2c->ret)
  96                 complete(&i2c->complete);
  97
  98         return IRQ_HANDLED;
  99 }
 100
 101 static int wmt_i2c_probe(struct platform_device *pdev)
 102 {
 103         struct device_node *np = pdev->dev.of_node;
 104         struct viai2c *i2c;
 105         struct i2c_adapter *adap;
 106         int err;
 107         u32 clk_rate;
 108
 109         err = viai2c_init(pdev, &i2c, VIAI2C_PLAT_WMT);
 110         if (err)
 111                 return err;
 112
 113         i2c->irq = platform_get_irq(pdev, 0);
 114         if (i2c->irq < 0)
 115                 return i2c->irq;
 116
 117         err = devm_request_irq(&pdev->dev, i2c->irq, wmt_i2c_isr,
 118                                0, pdev->name, i2c);
 119         if (err)
 120                 return dev_err_probe(&pdev->dev, err,
 121                                 "failed to request irq %i\n", i2c->irq);
 122
 123         i2c->clk = of_clk_get(np, 0);
 124         if (IS_ERR(i2c->clk)) {
 125                 dev_err(&pdev->dev, "unable to request clock\n");
 126                 return PTR_ERR(i2c->clk);
 127         }
 128
 129         err = of_property_read_u32(np, "clock-frequency", &clk_rate);
 130         if (!err && clk_rate == I2C_MAX_FAST_MODE_FREQ)
 131                 i2c->tcr = VIAI2C_TCR_FAST;
 132
 133         adap = &i2c->adapter;
 134         i2c_set_adapdata(adap, i2c);
 135         strscpy(adap->name, "WMT I2C adapter", sizeof(adap->name));
 136         adap->owner = THIS_MODULE;
 137         adap->algo = &wmt_i2c_algo;
 138         adap->dev.parent = &pdev->dev;
 139         adap->dev.of_node = pdev->dev.of_node;
 140
 141         err = wmt_i2c_reset_hardware(i2c);
 142         if (err) {
 143                 dev_err(&pdev->dev, "error initializing hardware\n");
 144                 return err;
 145         }
 146
 147         err = i2c_add_adapter(adap);
 148         if (err)
 149                 /* wmt_i2c_reset_hardware() enables i2c_dev->clk */
 150                 clk_disable_unprepare(i2c->clk);
 151
 152         return err;
 153 }
 154
 155 static void wmt_i2c_remove(struct platform_device *pdev)
 156 {
 157         struct viai2c *i2c = platform_get_drvdata(pdev);
 158
 159         /* Disable interrupts, clock and delete adapter */
 160         writew(0, i2c->base + VIAI2C_REG_IMR);
 161         clk_disable_unprepare(i2c->clk);
 162         i2c_del_adapter(&i2c->adapter);
 163 }
 164
 165 static const struct of_device_id wmt_i2c_dt_ids[] = {
 166         { .compatible = "wm,wm8505-i2c" },
 167         { /* Sentinel */ },
 168 };
 169
 170 static struct platform_driver wmt_i2c_driver = {
 171         .probe          = wmt_i2c_probe,
 172         .remove         = wmt_i2c_remove,
 173         .driver         = {
 174                 .name   = "wmt-i2c",
 175                 .of_match_table = wmt_i2c_dt_ids,
 176         },
 177 };
 178
 179 module_platform_driver(wmt_i2c_driver);
 180
 181 MODULE_DESCRIPTION("Wondermedia I2C controller driver");
 182 MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>");
 183 MODULE_LICENSE("GPL");
 184 MODULE_DEVICE_TABLE(of, wmt_i2c_dt_ids);