1 // SPDX-License-Identifier: GPL-2.0+
3 * Copyright (C) 2018 Arm Ltd
4 * Author: Liviu Dudau <liviu.dudau@foss.arm.com>
12 #include <linux/bitops.h>
13 #include <linux/delay.h>
16 #define SYS_CFGDATA 0xa0
18 #define SYS_CFGCTRL 0xa4
19 #define SYS_CFGCTRL_START BIT(31)
20 #define SYS_CFGCTRL_WRITE BIT(30)
22 #define SYS_CFGSTAT 0xa8
23 #define SYS_CFGSTAT_ERR BIT(1)
24 #define SYS_CFGSTAT_COMPLETE BIT(0)
26 struct vexpress_config_sysreg {
31 static int vexpress_config_exec(struct vexpress_config_sysreg *syscfg,
32 bool write, void *buf, int size)
34 u32 cmd, status, tries = 100;
36 cmd = (*(u32 *)buf) | SYS_CFGCTRL_START | (syscfg->site << 16);
39 /* write a canary in the data register for reads */
40 writel(0xdeadbeef, syscfg->addr + SYS_CFGDATA);
42 cmd |= SYS_CFGCTRL_WRITE;
43 writel(((u32 *)buf)[1], syscfg->addr + SYS_CFGDATA);
45 writel(0, syscfg->addr + SYS_CFGSTAT);
46 writel(cmd, syscfg->addr + SYS_CFGCTRL);
48 /* completion of command takes ages, go to sleep (150us) */
51 status = readl(syscfg->addr + SYS_CFGSTAT);
52 if (status & SYS_CFGSTAT_ERR)
54 } while (--tries && !(status & SYS_CFGSTAT_COMPLETE));
60 (*(u32 *)buf) = readl(syscfg->addr + SYS_CFGDATA);
65 static int vexpress_config_read(struct udevice *dev,
66 int offset, void *buf, int size)
68 struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
70 if (size != sizeof(u32))
73 return vexpress_config_exec(priv, false, buf, size);
76 static int vexpress_config_write(struct udevice *dev,
77 int offset, const void *buf, int size)
79 struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
81 if (size != sizeof(u32) * 2)
84 return vexpress_config_exec(priv, true, (void *)buf, size);
87 static struct misc_ops vexpress_config_ops = {
88 .read = vexpress_config_read,
89 .write = vexpress_config_write,
92 static int vexpress_config_probe(struct udevice *dev)
94 struct ofnode_phandle_args args;
95 struct vexpress_config_sysreg *priv;
99 err = dev_read_phandle_with_args(dev, "arm,vexpress,config-bridge",
104 prop = ofnode_get_property(args.node, "compatible", &prop_size);
105 if (!prop || (strncmp(prop, "arm,vexpress-sysreg", 19) != 0))
108 priv = calloc(1, sizeof(*priv));
112 dev_get_uclass_priv(dev) = priv;
113 priv->addr = ofnode_get_addr(args.node);
115 return dev_read_u32(dev, "arm,vexpress,site", &priv->site);
118 static const struct udevice_id vexpress_config_ids[] = {
119 { .compatible = "arm,vexpress,config-bus" },
123 U_BOOT_DRIVER(vexpress_config_drv) = {
124 .name = "vexpress_config_bus",
126 .of_match = vexpress_config_ids,
127 .bind = dm_scan_fdt_dev,
128 .probe = vexpress_config_probe,
129 .ops = &vexpress_config_ops,