drivers/mmc/host/sdhci-cns3xxx.c

   1 /*
   2  * SDHCI support for CNS3xxx SoC
   3  *
   4  * Copyright 2008 Cavium Networks
   5  * Copyright 2010 MontaVista Software, LLC.
   6  *
   7  * Authors: Scott Shu
   8  *          Anton Vorontsov <avorontsov@mvista.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/delay.h>
  16 #include <linux/device.h>
  17 #include <linux/mmc/host.h>
  18 #include <linux/module.h>
  19 #include <mach/cns3xxx.h>
  20 #include "sdhci-pltfm.h"
  21
  22 static unsigned int sdhci_cns3xxx_get_max_clk(struct sdhci_host *host)
  23 {
  24         return 150000000;
  25 }
  26
  27 static void sdhci_cns3xxx_set_clock(struct sdhci_host *host, unsigned int clock)
  28 {
  29         struct device *dev = mmc_dev(host->mmc);
  30         int div = 1;
  31         u16 clk;
  32         unsigned long timeout;
  33
  34         if (clock == host->clock)
  35                 return;
  36
  37         sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
  38
  39         if (clock == 0)
  40                 goto out;
  41
  42         while (host->max_clk / div > clock) {
  43                 /*
  44                  * On CNS3xxx divider grows linearly up to 4, and then
  45                  * exponentially up to 256.
  46                  */
  47                 if (div < 4)
  48                         div += 1;
  49                 else if (div < 256)
  50                         div *= 2;
  51                 else
  52                         break;
  53         }
  54
  55         dev_dbg(dev, "desired SD clock: %d, actual: %d\n",
  56                 clock, host->max_clk / div);
  57
  58         /* Divide by 3 is special. */
  59         if (div != 3)
  60                 div >>= 1;
  61
  62         clk = div << SDHCI_DIVIDER_SHIFT;
  63         clk |= SDHCI_CLOCK_INT_EN;
  64         sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
  65
  66         timeout = 20;
  67         while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
  68                         & SDHCI_CLOCK_INT_STABLE)) {
  69                 if (timeout == 0) {
  70                         dev_warn(dev, "clock is unstable");
  71                         break;
  72                 }
  73                 timeout--;
  74                 mdelay(1);
  75         }
  76
  77         clk |= SDHCI_CLOCK_CARD_EN;
  78         sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
  79 out:
  80         host->clock = clock;
  81 }
  82
  83 static struct sdhci_ops sdhci_cns3xxx_ops = {
  84         .get_max_clock  = sdhci_cns3xxx_get_max_clk,
  85         .set_clock      = sdhci_cns3xxx_set_clock,
  86 };
  87
  88 static struct sdhci_pltfm_data sdhci_cns3xxx_pdata = {
  89         .ops = &sdhci_cns3xxx_ops,
  90         .quirks = SDHCI_QUIRK_BROKEN_DMA |
  91                   SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
  92                   SDHCI_QUIRK_INVERTED_WRITE_PROTECT |
  93                   SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN |
  94                   SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
  95                   SDHCI_QUIRK_NONSTANDARD_CLOCK,
  96 };
  97
  98 static int __devinit sdhci_cns3xxx_probe(struct platform_device *pdev)
  99 {
 100         return sdhci_pltfm_register(pdev, &sdhci_cns3xxx_pdata);
 101 }
 102
 103 static int __devexit sdhci_cns3xxx_remove(struct platform_device *pdev)
 104 {
 105         return sdhci_pltfm_unregister(pdev);
 106 }
 107
 108 static struct platform_driver sdhci_cns3xxx_driver = {
 109         .driver         = {
 110                 .name   = "sdhci-cns3xxx",
 111                 .owner  = THIS_MODULE,
 112                 .pm     = SDHCI_PLTFM_PMOPS,
 113         },
 114         .probe          = sdhci_cns3xxx_probe,
 115         .remove         = __devexit_p(sdhci_cns3xxx_remove),
 116 };
 117
 118 module_platform_driver(sdhci_cns3xxx_driver);
 119
 120 MODULE_DESCRIPTION("SDHCI driver for CNS3xxx");
 121 MODULE_AUTHOR("Scott Shu, "
 122               "Anton Vorontsov <avorontsov@mvista.com>");
 123 MODULE_LICENSE("GPL v2");