drivers/misc/vexpress_config.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2018 Arm Ltd
   4  * Author: Liviu Dudau <liviu.dudau@foss.arm.com>
   5  *
   6  */
   7 #include <common.h>
   8 #include <dm.h>
   9 #include <malloc.h>
  10 #include <dm/read.h>
  11 #include <asm/io.h>
  12 #include <linux/bitops.h>
  13 #include <linux/delay.h>
  14 #include <misc.h>
  15
  16 #define SYS_CFGDATA             0xa0
  17
  18 #define SYS_CFGCTRL             0xa4
  19 #define SYS_CFGCTRL_START       BIT(31)
  20 #define SYS_CFGCTRL_WRITE       BIT(30)
  21
  22 #define SYS_CFGSTAT             0xa8
  23 #define SYS_CFGSTAT_ERR         BIT(1)
  24 #define SYS_CFGSTAT_COMPLETE    BIT(0)
  25
  26 struct vexpress_config_sysreg {
  27         phys_addr_t addr;
  28         u32 site;
  29 };
  30
  31 static int vexpress_config_exec(struct vexpress_config_sysreg *syscfg,
  32                                 bool write, void *buf, int size)
  33 {
  34         u32 cmd, status, tries = 100;
  35
  36         cmd = (*(u32 *)buf) | SYS_CFGCTRL_START | (syscfg->site << 16);
  37
  38         if (!write) {
  39                 /* write a canary in the data register for reads */
  40                 writel(0xdeadbeef, syscfg->addr + SYS_CFGDATA);
  41         } else {
  42                 cmd |= SYS_CFGCTRL_WRITE;
  43                 writel(((u32 *)buf)[1], syscfg->addr + SYS_CFGDATA);
  44         }
  45         writel(0, syscfg->addr + SYS_CFGSTAT);
  46         writel(cmd, syscfg->addr + SYS_CFGCTRL);
  47
  48         /* completion of command takes ages, go to sleep (150us) */
  49         do {
  50                 udelay(150);
  51                 status = readl(syscfg->addr + SYS_CFGSTAT);
  52                 if (status & SYS_CFGSTAT_ERR)
  53                         return -EFAULT;
  54         } while (--tries && !(status & SYS_CFGSTAT_COMPLETE));
  55
  56         if (!tries)
  57                 return -ETIMEDOUT;
  58
  59         if (!write)
  60                 (*(u32 *)buf) = readl(syscfg->addr + SYS_CFGDATA);
  61
  62         return 0;
  63 }
  64
  65 static int vexpress_config_read(struct udevice *dev,
  66                                 int offset, void *buf, int size)
  67 {
  68         struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
  69
  70         if (size != sizeof(u32))
  71                 return -EINVAL;
  72
  73         return vexpress_config_exec(priv, false, buf, size);
  74 }
  75
  76 static int vexpress_config_write(struct udevice *dev,
  77                                  int offset, const void *buf, int size)
  78 {
  79         struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
  80
  81         if (size != sizeof(u32) * 2)
  82                 return -EINVAL;
  83
  84         return vexpress_config_exec(priv, true, (void *)buf, size);
  85 }
  86
  87 static struct misc_ops vexpress_config_ops = {
  88         .read = vexpress_config_read,
  89         .write = vexpress_config_write,
  90 };
  91
  92 static int vexpress_config_probe(struct udevice *dev)
  93 {
  94         struct ofnode_phandle_args args;
  95         struct vexpress_config_sysreg *priv;
  96         const char *prop;
  97         int err, prop_size;
  98
  99         err = dev_read_phandle_with_args(dev, "arm,vexpress,config-bridge",
 100                                          NULL, 0, 0, &args);
 101         if (err)
 102                 return err;
 103
 104         prop = ofnode_get_property(args.node, "compatible", &prop_size);
 105         if (!prop || (strncmp(prop, "arm,vexpress-sysreg", 19) != 0))
 106                 return -ENOENT;
 107
 108         priv = calloc(1, sizeof(*priv));
 109         if (!priv)
 110                 return -ENOMEM;
 111
 112         dev->uclass_priv = priv;
 113         priv->addr = ofnode_get_addr(args.node);
 114
 115         return dev_read_u32(dev, "arm,vexpress,site", &priv->site);
 116 }
 117
 118 static const struct udevice_id vexpress_config_ids[] = {
 119         { .compatible = "arm,vexpress,config-bus" },
 120         { }
 121 };
 122
 123 U_BOOT_DRIVER(vexpress_config_drv) = {
 124         .name = "vexpress_config_bus",
 125         .id = UCLASS_MISC,
 126         .of_match = vexpress_config_ids,
 127         .bind = dm_scan_fdt_dev,
 128         .probe = vexpress_config_probe,
 129         .ops = &vexpress_config_ops,
 130 };