tadpole.c

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/* tadpole.c: Probing for the tadpole clock stopping h/w at boot time.
 *
 * Copyright (C) 1996 David Redman ([email protected])
 */

#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>

#include <asm/asi.h>
#include <asm/oplib.h>
#include <asm/io.h>

#define MACIO_SCSI_CSR_ADDR 0x78400000
#define MACIO_EN_DMA        0x00000200
#define CLOCK_INIT_DONE     1

static int clk_state;
static volatile unsigned char *clk_ctrl;
void (*cpu_pwr_save)(void);

static inline unsigned int ldphys(unsigned int addr)
{
    unsigned long data;
    
    __asm__ __volatile__("\n\tlda [%1] %2, %0\n\t" : 
                 "=r" (data) :
                 "r" (addr), "i" (ASI_M_BYPASS));
    return data;
}

static void clk_init(void)
{
    __asm__ __volatile__("mov 0x6c, %%g1\n\t"
                 "mov 0x4c, %%g2\n\t"
                 "mov 0xdf, %%g3\n\t"
                 "stb %%g1, [%0+3]\n\t"
                 "stb %%g2, [%0+3]\n\t"
                 "stb %%g3, [%0+3]\n\t" : :
                 "r" (clk_ctrl) :
                 "g1", "g2", "g3");
}

static void clk_slow(void)
{
    __asm__ __volatile__("mov 0xcc, %%g2\n\t"
                 "mov 0x4c, %%g3\n\t"
                 "mov 0xcf, %%g4\n\t"
                 "mov 0xdf, %%g5\n\t"
                 "stb %%g2, [%0+3]\n\t"
                 "stb %%g3, [%0+3]\n\t"
                 "stb %%g4, [%0+3]\n\t"
                 "stb %%g5, [%0+3]\n\t" : :
                 "r" (clk_ctrl) :
                 "g2", "g3", "g4", "g5");
}

/*
 * Tadpole is guaranteed to be UP, using local_irq_save.
 */
static void tsu_clockstop(void)
{
    unsigned int mcsr;
    unsigned long flags;

    if (!clk_ctrl)
        return;
    if (!(clk_state & CLOCK_INIT_DONE)) {
        local_irq_save(flags);
        clk_init();
        clk_state |= CLOCK_INIT_DONE;       /* all done */
        local_irq_restore(flags);
        return;
    }
    if (!(clk_ctrl[2] & 1))
        return;               /* no speed up yet */

    local_irq_save(flags);

    /* if SCSI DMA in progress, don't slow clock */
    mcsr = ldphys(MACIO_SCSI_CSR_ADDR);
    if ((mcsr&MACIO_EN_DMA) != 0) {
        local_irq_restore(flags);
        return;
    }
    /* TODO... the minimum clock setting ought to increase the
     * memory refresh interval..
     */
    clk_slow();
    local_irq_restore(flags);
}

static void swift_clockstop(void)
{
    if (!clk_ctrl)
        return;
    clk_ctrl[0] = 0;
}

void __init clock_stop_probe(void)
{
    phandle node, clk_nd;
    char name[20];
    
    prom_getstring(prom_root_node, "name", name, sizeof(name));
    if (strncmp(name, "Tadpole", 7))
        return;
    node = prom_getchild(prom_root_node);
    node = prom_searchsiblings(node, "obio");
    node = prom_getchild(node);
    clk_nd = prom_searchsiblings(node, "clk-ctrl");
    if (!clk_nd)
        return;
    printk("Clock Stopping h/w detected... ");
    clk_ctrl = (char *) prom_getint(clk_nd, "address");
    clk_state = 0;
    if (name[10] == '\0') {
        cpu_pwr_save = tsu_clockstop;
        printk("enabled (S3)\n");
    } else if ((name[10] == 'X') || (name[10] == 'G')) {
        cpu_pwr_save = swift_clockstop;
        printk("enabled (%s)\n",name+7);
    } else
        printk("disabled %s\n",name+7);
}