slcr.c
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/*
* Xilinx SLCR driver
*
* Copyright (c) 2011-2013 Xilinx Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA
* 02139, USA.
*/
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/clk/zynq.h>
#include "common.h"
/* register offsets */
#define SLCR_UNLOCK_OFFSET 0x8 /* SCLR unlock register */
#define SLCR_PS_RST_CTRL_OFFSET 0x200 /* PS Software Reset Control */
#define SLCR_A9_CPU_RST_CTRL_OFFSET 0x244 /* CPU Software Reset Control */
#define SLCR_REBOOT_STATUS_OFFSET 0x258 /* PS Reboot Status */
#define SLCR_UNLOCK_MAGIC 0xDF0D
#define SLCR_A9_CPU_CLKSTOP 0x10
#define SLCR_A9_CPU_RST 0x1
void __iomem *zynq_slcr_base;
/**
* zynq_slcr_system_reset - Reset the entire system.
*/
void zynq_slcr_system_reset(void)
{
u32 reboot;
/*
* Unlock the SLCR then reset the system.
* Note that this seems to require raw i/o
* functions or there's a lockup?
*/
writel(SLCR_UNLOCK_MAGIC, zynq_slcr_base + SLCR_UNLOCK_OFFSET);
/*
* Clear 0x0F000000 bits of reboot status register to workaround
* the FSBL not loading the bitstream after soft-reboot
* This is a temporary solution until we know more.
*/
reboot = readl(zynq_slcr_base + SLCR_REBOOT_STATUS_OFFSET);
writel(reboot & 0xF0FFFFFF, zynq_slcr_base + SLCR_REBOOT_STATUS_OFFSET);
writel(1, zynq_slcr_base + SLCR_PS_RST_CTRL_OFFSET);
}
/**
* zynq_slcr_cpu_start - Start cpu
* @cpu: cpu number
*/
void zynq_slcr_cpu_start(int cpu)
{
u32 reg = readl(zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
reg &= ~(SLCR_A9_CPU_RST << cpu);
writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
reg &= ~(SLCR_A9_CPU_CLKSTOP << cpu);
writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
}
/**
* zynq_slcr_cpu_stop - Stop cpu
* @cpu: cpu number
*/
void zynq_slcr_cpu_stop(int cpu)
{
u32 reg = readl(zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
reg |= (SLCR_A9_CPU_CLKSTOP | SLCR_A9_CPU_RST) << cpu;
writel(reg, zynq_slcr_base + SLCR_A9_CPU_RST_CTRL_OFFSET);
}
/**
* zynq_slcr_init
* Returns 0 on success, negative errno otherwise.
*
* Called early during boot from platform code to remap SLCR area.
*/
int __init zynq_slcr_init(void)
{
struct device_node *np;
np = of_find_compatible_node(NULL, NULL, "xlnx,zynq-slcr");
if (!np) {
pr_err("%s: no slcr node found\n", __func__);
BUG();
}
zynq_slcr_base = of_iomap(np, 0);
if (!zynq_slcr_base) {
pr_err("%s: Unable to map I/O memory\n", __func__);
BUG();
}
/* unlock the SLCR so that registers can be changed */
writel(SLCR_UNLOCK_MAGIC, zynq_slcr_base + SLCR_UNLOCK_OFFSET);
pr_info("%s mapped to %p\n", np->name, zynq_slcr_base);
zynq_clock_init(zynq_slcr_base);
of_node_put(np);
return 0;
}