LXR linux/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
  22static unsigned int sdhci_cns3xxx_get_max_clk(struct sdhci_host *host)
  23{
  24        return 150000000;
  25}
  26
  27static 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);
  79out:
  80        host->clock = clock;
  81}
  82
  83static struct sdhci_ops sdhci_cns3xxx_ops = {
  84        .get_max_clock  = sdhci_cns3xxx_get_max_clk,
  85        .set_clock      = sdhci_cns3xxx_set_clock,
  86};
  87
  88static 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
  98static int __devinit sdhci_cns3xxx_probe(struct platform_device *pdev)
  99{
 100        return sdhci_pltfm_register(pdev, &sdhci_cns3xxx_pdata);
 101}
 102
 103static int __devexit sdhci_cns3xxx_remove(struct platform_device *pdev)
 104{
 105        return sdhci_pltfm_unregister(pdev);
 106}
 107
 108static 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
 118module_platform_driver(sdhci_cns3xxx_driver);
 119
 120MODULE_DESCRIPTION("SDHCI driver for CNS3xxx");
 121MODULE_AUTHOR("Scott Shu, "
 122              "Anton Vorontsov <avorontsov@mvista.com>");
 123MODULE_LICENSE("GPL v2");
 124