LXR uboot/drivers/serial/serial_bcm283x

   1/*
   2 * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org>
   3 *
   4 * Derived from pl01x code:
   5 *
   6 * (C) Copyright 2000
   7 * Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
   8 *
   9 * (C) Copyright 2004
  10 * ARM Ltd.
  11 * Philippe Robin, <philippe.robin@arm.com>
  12 *
  13 * SPDX-License-Identifier:     GPL-2.0+
  14 */
  15
  16/* Simple U-Boot driver for the BCM283x mini UART */
  17
  18#include <common.h>
  19#include <dm.h>
  20#include <errno.h>
  21#include <watchdog.h>
  22#include <asm/io.h>
  23#include <serial.h>
  24#include <dm/platform_data/serial_bcm283x_mu.h>
  25#include <linux/compiler.h>
  26#include <fdtdec.h>
  27
  28struct bcm283x_mu_regs {
  29        u32 io;
  30        u32 iir;
  31        u32 ier;
  32        u32 lcr;
  33        u32 mcr;
  34        u32 lsr;
  35        u32 msr;
  36        u32 scratch;
  37        u32 cntl;
  38        u32 stat;
  39        u32 baud;
  40};
  41
  42#define BCM283X_MU_LCR_DATA_SIZE_8      3
  43
  44#define BCM283X_MU_LSR_TX_IDLE          BIT(6)
  45/* This actually means not full, but is named not empty in the docs */
  46#define BCM283X_MU_LSR_TX_EMPTY         BIT(5)
  47#define BCM283X_MU_LSR_RX_READY         BIT(0)
  48
  49struct bcm283x_mu_priv {
  50        struct bcm283x_mu_regs *regs;
  51};
  52
  53static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
  54{
  55        struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
  56        struct bcm283x_mu_priv *priv = dev_get_priv(dev);
  57        struct bcm283x_mu_regs *regs = priv->regs;
  58        u32 divider;
  59
  60        if (plat->skip_init)
  61                return 0;
  62
  63        divider = plat->clock / (baudrate * 8);
  64
  65        writel(BCM283X_MU_LCR_DATA_SIZE_8, &regs->lcr);
  66        writel(divider - 1, &regs->baud);
  67
  68        return 0;
  69}
  70
  71static int bcm283x_mu_serial_probe(struct udevice *dev)
  72{
  73        struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
  74        struct bcm283x_mu_priv *priv = dev_get_priv(dev);
  75
  76        if (plat->disabled)
  77                return -ENODEV;
  78
  79        priv->regs = (struct bcm283x_mu_regs *)plat->base;
  80
  81        return 0;
  82}
  83
  84static int bcm283x_mu_serial_getc(struct udevice *dev)
  85{
  86        struct bcm283x_mu_priv *priv = dev_get_priv(dev);
  87        struct bcm283x_mu_regs *regs = priv->regs;
  88        u32 data;
  89
  90        /* Wait until there is data in the FIFO */
  91        if (!(readl(&regs->lsr) & BCM283X_MU_LSR_RX_READY))
  92                return -EAGAIN;
  93
  94        data = readl(&regs->io);
  95
  96        return (int)data;
  97}
  98
  99static int bcm283x_mu_serial_putc(struct udevice *dev, const char data)
 100{
 101        struct bcm283x_mu_priv *priv = dev_get_priv(dev);
 102        struct bcm283x_mu_regs *regs = priv->regs;
 103
 104        /* Wait until there is space in the FIFO */
 105        if (!(readl(&regs->lsr) & BCM283X_MU_LSR_TX_EMPTY))
 106                return -EAGAIN;
 107
 108        /* Send the character */
 109        writel(data, &regs->io);
 110
 111        return 0;
 112}
 113
 114static int bcm283x_mu_serial_pending(struct udevice *dev, bool input)
 115{
 116        struct bcm283x_mu_priv *priv = dev_get_priv(dev);
 117        struct bcm283x_mu_regs *regs = priv->regs;
 118        unsigned int lsr = readl(&regs->lsr);
 119
 120        if (input) {
 121                WATCHDOG_RESET();
 122                return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0;
 123        } else {
 124                return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1;
 125        }
 126}
 127
 128static const struct dm_serial_ops bcm283x_mu_serial_ops = {
 129        .putc = bcm283x_mu_serial_putc,
 130        .pending = bcm283x_mu_serial_pending,
 131        .getc = bcm283x_mu_serial_getc,
 132        .setbrg = bcm283x_mu_serial_setbrg,
 133};
 134
 135U_BOOT_DRIVER(serial_bcm283x_mu) = {
 136        .name = "serial_bcm283x_mu",
 137        .id = UCLASS_SERIAL,
 138        .platdata_auto_alloc_size = sizeof(struct bcm283x_mu_serial_platdata),
 139        .probe = bcm283x_mu_serial_probe,
 140        .ops = &bcm283x_mu_serial_ops,
 141        .flags = DM_FLAG_PRE_RELOC,
 142        .priv_auto_alloc_size = sizeof(struct bcm283x_mu_priv),
 143};
 144