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 "sdhci-pltfm.h"
  20
  21 static unsigned int sdhci_cns3xxx_get_max_clk(struct sdhci_host *host)
  22 {
  23         return 150000000;
  24 }
  25
  26 static void sdhci_cns3xxx_set_clock(struct sdhci_host *host, unsigned int clock)
  27 {
  28         struct device *dev = mmc_dev(host->mmc);
  29         int div = 1;
  30         u16 clk;
  31         unsigned long timeout;
  32
  33         if (clock == host->clock)
  34                 return;
  35
  36         sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
  37
  38         if (clock == 0)
  39                 goto out;
  40
  41         while (host->max_clk / div > clock) {
  42                 /*
  43                  * On CNS3xxx divider grows linearly up to 4, and then
  44                  * exponentially up to 256.
  45                  */
  46                 if (div < 4)
  47                         div += 1;
  48                 else if (div < 256)
  49                         div *= 2;
  50                 else
  51                         break;
  52         }
  53
  54         dev_dbg(dev, "desired SD clock: %d, actual: %d\n",
  55                 clock, host->max_clk / div);
  56
  57         /* Divide by 3 is special. */
  58         if (div != 3)
  59                 div >>= 1;
  60
  61         clk = div << SDHCI_DIVIDER_SHIFT;
  62         clk |= SDHCI_CLOCK_INT_EN;
  63         sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
  64
  65         timeout = 20;
  66         while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
  67                         & SDHCI_CLOCK_INT_STABLE)) {
  68                 if (timeout == 0) {
  69                         dev_warn(dev, "clock is unstable");
  70                         break;
  71                 }
  72                 timeout--;
  73                 mdelay(1);
  74         }
  75
  76         clk |= SDHCI_CLOCK_CARD_EN;
  77         sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
  78 out:
  79         host->clock = clock;
  80 }
  81
  82 static const struct sdhci_ops sdhci_cns3xxx_ops = {
  83         .get_max_clock  = sdhci_cns3xxx_get_max_clk,
  84         .set_clock      = sdhci_cns3xxx_set_clock,
  85         .set_bus_width  = sdhci_set_bus_width,
  86         .reset          = sdhci_reset,
  87 };
  88
  89 static const struct sdhci_pltfm_data sdhci_cns3xxx_pdata = {
  90         .ops = &sdhci_cns3xxx_ops,
  91         .quirks = SDHCI_QUIRK_BROKEN_DMA |
  92                   SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
  93                   SDHCI_QUIRK_INVERTED_WRITE_PROTECT |
  94                   SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN |
  95                   SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
  96                   SDHCI_QUIRK_NONSTANDARD_CLOCK,
  97 };
  98
  99 static int sdhci_cns3xxx_probe(struct platform_device *pdev)
 100 {
 101         return sdhci_pltfm_register(pdev, &sdhci_cns3xxx_pdata, 0);
 102 }
 103
 104 static int sdhci_cns3xxx_remove(struct platform_device *pdev)
 105 {
 106         return sdhci_pltfm_unregister(pdev);
 107 }
 108
 109 static struct platform_driver sdhci_cns3xxx_driver = {
 110         .driver         = {
 111                 .name   = "sdhci-cns3xxx",
 112                 .owner  = THIS_MODULE,
 113                 .pm     = SDHCI_PLTFM_PMOPS,
 114         },
 115         .probe          = sdhci_cns3xxx_probe,
 116         .remove         = sdhci_cns3xxx_remove,
 117 };
 118
 119 module_platform_driver(sdhci_cns3xxx_driver);
 120
 121 MODULE_DESCRIPTION("SDHCI driver for CNS3xxx");
 122 MODULE_AUTHOR("Scott Shu, "
 123               "Anton Vorontsov <avorontsov@mvista.com>");
 124 MODULE_LICENSE("GPL v2");