mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
![Finn Thain](/assets/img/avatar_default.png)
Add a platform clocksource by adapting the existing arch_gettimeoffset implementation. Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Acked-by: Linus Walleij <linus.walleij@linaro.org> Tested-by: Stan Johnson <userm57@yahoo.com> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
655 lines
17 KiB
C
655 lines
17 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* 6522 Versatile Interface Adapter (VIA)
|
|
*
|
|
* There are two of these on the Mac II. Some IRQs are vectored
|
|
* via them as are assorted bits and bobs - eg RTC, ADB.
|
|
*
|
|
* CSA: Motorola seems to have removed documentation on the 6522 from
|
|
* their web site; try
|
|
* http://nerini.drf.com/vectrex/other/text/chips/6522/
|
|
* http://www.zymurgy.net/classic/vic20/vicdet1.htm
|
|
* and
|
|
* http://193.23.168.87/mikro_laborversuche/via_iobaustein/via6522_1.html
|
|
* for info. A full-text web search on 6522 AND VIA will probably also
|
|
* net some usefulness. <cananian@alumni.princeton.edu> 20apr1999
|
|
*
|
|
* Additional data is here (the SY6522 was used in the Mac II etc):
|
|
* http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
|
|
* http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf
|
|
*
|
|
* PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b
|
|
* by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org)
|
|
*
|
|
*/
|
|
|
|
#include <linux/clocksource.h>
|
|
#include <linux/types.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/init.h>
|
|
#include <linux/module.h>
|
|
#include <linux/irq.h>
|
|
|
|
#include <asm/macintosh.h>
|
|
#include <asm/macints.h>
|
|
#include <asm/mac_via.h>
|
|
#include <asm/mac_psc.h>
|
|
#include <asm/mac_oss.h>
|
|
|
|
volatile __u8 *via1, *via2;
|
|
int rbv_present;
|
|
int via_alt_mapping;
|
|
EXPORT_SYMBOL(via_alt_mapping);
|
|
static __u8 rbv_clear;
|
|
|
|
/*
|
|
* Globals for accessing the VIA chip registers without having to
|
|
* check if we're hitting a real VIA or an RBV. Normally you could
|
|
* just hit the combined register (ie, vIER|rIER) but that seems to
|
|
* break on AV Macs...probably because they actually decode more than
|
|
* eight address bits. Why can't Apple engineers at least be
|
|
* _consistently_ lazy? - 1999-05-21 (jmt)
|
|
*/
|
|
|
|
static int gIER,gIFR,gBufA,gBufB;
|
|
|
|
/*
|
|
* On Macs with a genuine VIA chip there is no way to mask an individual slot
|
|
* interrupt. This limitation also seems to apply to VIA clone logic cores in
|
|
* Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
|
|
*
|
|
* We used to fake it by configuring the relevant VIA pin as an output
|
|
* (to mask the interrupt) or input (to unmask). That scheme did not work on
|
|
* (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
|
|
* circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
|
|
* p. 10-11 etc) but VIA outputs are not (see datasheet).
|
|
*
|
|
* Driving these outputs high must cause the VIA to source current and the
|
|
* card to sink current when it asserts /NMRQ. Current will flow but the pin
|
|
* voltage is uncertain and so the /NMRQ condition may still cause a transition
|
|
* at the VIA2 CA1 input (which explains the lost interrupts). A side effect
|
|
* is that a disabled slot IRQ can never be tested as pending or not.
|
|
*
|
|
* Driving these outputs low doesn't work either. All the slot /NMRQ lines are
|
|
* (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
|
|
* The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
|
|
* disabled /NMRQ line low, the falling edge immediately triggers a CA1
|
|
* interrupt and all slot interrupts after that will generate no transition
|
|
* and therefore no interrupt, even after being re-enabled.
|
|
*
|
|
* So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
|
|
* track of their states. When any slot IRQ becomes disabled we mask the CA1
|
|
* umbrella interrupt. Only when all slot IRQs become enabled do we unmask
|
|
* the CA1 interrupt. It must remain enabled even when cards have no interrupt
|
|
* handler registered. Drivers must therefore disable a slot interrupt at the
|
|
* device before they call free_irq (like shared and autovector interrupts).
|
|
*
|
|
* There is also a related problem when MacOS is used to boot Linux. A network
|
|
* card brought up by a MacOS driver may raise an interrupt while Linux boots.
|
|
* This can be fatal since it can't be handled until the right driver loads
|
|
* (if such a driver exists at all). Apparently related to this hardware
|
|
* limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
|
|
* interrupt with no driver would crash MacOS (the book was written before
|
|
* the appearance of Macs with RBV or OSS).
|
|
*/
|
|
|
|
static u8 nubus_disabled;
|
|
|
|
void via_debug_dump(void);
|
|
static void via_nubus_init(void);
|
|
|
|
/*
|
|
* Initialize the VIAs
|
|
*
|
|
* First we figure out where they actually _are_ as well as what type of
|
|
* VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
|
|
* Then we pretty much clear them out and disable all IRQ sources.
|
|
*/
|
|
|
|
void __init via_init(void)
|
|
{
|
|
via1 = (void *)VIA1_BASE;
|
|
pr_debug("VIA1 detected at %p\n", via1);
|
|
|
|
if (oss_present) {
|
|
via2 = NULL;
|
|
rbv_present = 0;
|
|
} else {
|
|
switch (macintosh_config->via_type) {
|
|
|
|
/* IIci, IIsi, IIvx, IIvi (P6xx), LC series */
|
|
|
|
case MAC_VIA_IICI:
|
|
via2 = (void *)RBV_BASE;
|
|
pr_debug("VIA2 (RBV) detected at %p\n", via2);
|
|
rbv_present = 1;
|
|
if (macintosh_config->ident == MAC_MODEL_LCIII) {
|
|
rbv_clear = 0x00;
|
|
} else {
|
|
/* on most RBVs (& unlike the VIAs), you */
|
|
/* need to set bit 7 when you write to IFR */
|
|
/* in order for your clear to occur. */
|
|
rbv_clear = 0x80;
|
|
}
|
|
gIER = rIER;
|
|
gIFR = rIFR;
|
|
gBufA = rSIFR;
|
|
gBufB = rBufB;
|
|
break;
|
|
|
|
/* Quadra and early MacIIs agree on the VIA locations */
|
|
|
|
case MAC_VIA_QUADRA:
|
|
case MAC_VIA_II:
|
|
via2 = (void *) VIA2_BASE;
|
|
pr_debug("VIA2 detected at %p\n", via2);
|
|
rbv_present = 0;
|
|
rbv_clear = 0x00;
|
|
gIER = vIER;
|
|
gIFR = vIFR;
|
|
gBufA = vBufA;
|
|
gBufB = vBufB;
|
|
break;
|
|
|
|
default:
|
|
panic("UNKNOWN VIA TYPE");
|
|
}
|
|
}
|
|
|
|
#ifdef DEBUG_VIA
|
|
via_debug_dump();
|
|
#endif
|
|
|
|
/*
|
|
* Shut down all IRQ sources, reset the timers, and
|
|
* kill the timer latch on VIA1.
|
|
*/
|
|
|
|
via1[vIER] = 0x7F;
|
|
via1[vIFR] = 0x7F;
|
|
via1[vT1LL] = 0;
|
|
via1[vT1LH] = 0;
|
|
via1[vT1CL] = 0;
|
|
via1[vT1CH] = 0;
|
|
via1[vT2CL] = 0;
|
|
via1[vT2CH] = 0;
|
|
via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
|
|
via1[vACR] &= ~0x03; /* disable port A & B latches */
|
|
|
|
/*
|
|
* SE/30: disable video IRQ
|
|
*/
|
|
|
|
if (macintosh_config->ident == MAC_MODEL_SE30) {
|
|
via1[vDirB] |= 0x40;
|
|
via1[vBufB] |= 0x40;
|
|
}
|
|
|
|
switch (macintosh_config->adb_type) {
|
|
case MAC_ADB_IOP:
|
|
case MAC_ADB_II:
|
|
case MAC_ADB_PB1:
|
|
/*
|
|
* Set the RTC bits to a known state: all lines to outputs and
|
|
* RTC disabled (yes that's 0 to enable and 1 to disable).
|
|
*/
|
|
via1[vDirB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData;
|
|
via1[vBufB] |= VIA1B_vRTCEnb | VIA1B_vRTCClk;
|
|
break;
|
|
}
|
|
|
|
/* Everything below this point is VIA2/RBV only... */
|
|
|
|
if (oss_present)
|
|
return;
|
|
|
|
if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
|
|
(macintosh_config->adb_type != MAC_ADB_PB1) &&
|
|
(macintosh_config->adb_type != MAC_ADB_PB2) &&
|
|
(macintosh_config->ident != MAC_MODEL_C660) &&
|
|
(macintosh_config->ident != MAC_MODEL_Q840)) {
|
|
via_alt_mapping = 1;
|
|
via1[vDirB] |= 0x40;
|
|
via1[vBufB] &= ~0x40;
|
|
} else {
|
|
via_alt_mapping = 0;
|
|
}
|
|
|
|
/*
|
|
* Now initialize VIA2. For RBV we just kill all interrupts;
|
|
* for a regular VIA we also reset the timers and stuff.
|
|
*/
|
|
|
|
via2[gIER] = 0x7F;
|
|
via2[gIFR] = 0x7F | rbv_clear;
|
|
if (!rbv_present) {
|
|
via2[vT1LL] = 0;
|
|
via2[vT1LH] = 0;
|
|
via2[vT1CL] = 0;
|
|
via2[vT1CH] = 0;
|
|
via2[vT2CL] = 0;
|
|
via2[vT2CH] = 0;
|
|
via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
|
|
via2[vACR] &= ~0x03; /* disable port A & B latches */
|
|
}
|
|
|
|
via_nubus_init();
|
|
|
|
/* Everything below this point is VIA2 only... */
|
|
|
|
if (rbv_present)
|
|
return;
|
|
|
|
/*
|
|
* Set vPCR for control line interrupts.
|
|
*
|
|
* CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
|
|
*
|
|
* Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
|
|
* Testing reveals that PowerBooks do too. However, the SE/30
|
|
* schematic diagram shows an active high NCR5380 IRQ line.
|
|
*/
|
|
|
|
pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
|
|
if (macintosh_config->via_type == MAC_VIA_II) {
|
|
/* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
|
|
via2[vPCR] = 0x66;
|
|
} else {
|
|
/* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
|
|
via2[vPCR] = 0x22;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Debugging dump, used in various places to see what's going on.
|
|
*/
|
|
|
|
void via_debug_dump(void)
|
|
{
|
|
printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
|
|
(uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
|
|
printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
|
|
(uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
|
|
if (!via2)
|
|
return;
|
|
if (rbv_present) {
|
|
printk(KERN_DEBUG "VIA2: IFR = 0x%02X IER = 0x%02X\n",
|
|
(uint) via2[rIFR], (uint) via2[rIER]);
|
|
printk(KERN_DEBUG " SIFR = 0x%02X SIER = 0x%02X\n",
|
|
(uint) via2[rSIFR], (uint) via2[rSIER]);
|
|
} else {
|
|
printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
|
|
(uint) via2[vDirA], (uint) via2[vDirB],
|
|
(uint) via2[vACR]);
|
|
printk(KERN_DEBUG " PCR = 0x%02X IFR = 0x%02X IER = 0x%02X\n",
|
|
(uint) via2[vPCR],
|
|
(uint) via2[vIFR], (uint) via2[vIER]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Flush the L2 cache on Macs that have it by flipping
|
|
* the system into 24-bit mode for an instant.
|
|
*/
|
|
|
|
void via_flush_cache(void)
|
|
{
|
|
via2[gBufB] &= ~VIA2B_vMode32;
|
|
via2[gBufB] |= VIA2B_vMode32;
|
|
}
|
|
|
|
/*
|
|
* Return the status of the L2 cache on a IIci
|
|
*/
|
|
|
|
int via_get_cache_disable(void)
|
|
{
|
|
/* Safeguard against being called accidentally */
|
|
if (!via2) {
|
|
printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
|
|
return 1;
|
|
}
|
|
|
|
return (int) via2[gBufB] & VIA2B_vCDis;
|
|
}
|
|
|
|
/*
|
|
* Initialize VIA2 for Nubus access
|
|
*/
|
|
|
|
static void __init via_nubus_init(void)
|
|
{
|
|
/* unlock nubus transactions */
|
|
|
|
if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
|
|
(macintosh_config->adb_type != MAC_ADB_PB2)) {
|
|
/* set the line to be an output on non-RBV machines */
|
|
if (!rbv_present)
|
|
via2[vDirB] |= 0x02;
|
|
|
|
/* this seems to be an ADB bit on PMU machines */
|
|
/* according to MkLinux. -- jmt */
|
|
via2[gBufB] |= 0x02;
|
|
}
|
|
|
|
/*
|
|
* Disable the slot interrupts. On some hardware that's not possible.
|
|
* On some hardware it's unclear what all of these I/O lines do.
|
|
*/
|
|
|
|
switch (macintosh_config->via_type) {
|
|
case MAC_VIA_II:
|
|
case MAC_VIA_QUADRA:
|
|
pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
|
|
break;
|
|
case MAC_VIA_IICI:
|
|
/* RBV. Disable all the slot interrupts. SIER works like IER. */
|
|
via2[rSIER] = 0x7F;
|
|
break;
|
|
}
|
|
}
|
|
|
|
void via_nubus_irq_startup(int irq)
|
|
{
|
|
int irq_idx = IRQ_IDX(irq);
|
|
|
|
switch (macintosh_config->via_type) {
|
|
case MAC_VIA_II:
|
|
case MAC_VIA_QUADRA:
|
|
/* Make the port A line an input. Probably redundant. */
|
|
if (macintosh_config->via_type == MAC_VIA_II) {
|
|
/* The top two bits are RAM size outputs. */
|
|
via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
|
|
} else {
|
|
/* Allow NuBus slots 9 through F. */
|
|
via2[vDirA] &= 0x80 | ~(1 << irq_idx);
|
|
}
|
|
/* fall through */
|
|
case MAC_VIA_IICI:
|
|
via_irq_enable(irq);
|
|
break;
|
|
}
|
|
}
|
|
|
|
void via_nubus_irq_shutdown(int irq)
|
|
{
|
|
switch (macintosh_config->via_type) {
|
|
case MAC_VIA_II:
|
|
case MAC_VIA_QUADRA:
|
|
/* Ensure that the umbrella CA1 interrupt remains enabled. */
|
|
via_irq_enable(irq);
|
|
break;
|
|
case MAC_VIA_IICI:
|
|
via_irq_disable(irq);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
|
|
* via6522.c :-), disable/pending masks added.
|
|
*/
|
|
|
|
#define VIA_TIMER_1_INT BIT(6)
|
|
|
|
void via1_irq(struct irq_desc *desc)
|
|
{
|
|
int irq_num;
|
|
unsigned char irq_bit, events;
|
|
|
|
events = via1[vIFR] & via1[vIER] & 0x7F;
|
|
if (!events)
|
|
return;
|
|
|
|
irq_num = IRQ_MAC_TIMER_1;
|
|
irq_bit = VIA_TIMER_1_INT;
|
|
if (events & irq_bit) {
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
via1[vIFR] = irq_bit;
|
|
generic_handle_irq(irq_num);
|
|
local_irq_restore(flags);
|
|
|
|
events &= ~irq_bit;
|
|
if (!events)
|
|
return;
|
|
}
|
|
|
|
irq_num = VIA1_SOURCE_BASE;
|
|
irq_bit = 1;
|
|
do {
|
|
if (events & irq_bit) {
|
|
via1[vIFR] = irq_bit;
|
|
generic_handle_irq(irq_num);
|
|
}
|
|
++irq_num;
|
|
irq_bit <<= 1;
|
|
} while (events >= irq_bit);
|
|
}
|
|
|
|
static void via2_irq(struct irq_desc *desc)
|
|
{
|
|
int irq_num;
|
|
unsigned char irq_bit, events;
|
|
|
|
events = via2[gIFR] & via2[gIER] & 0x7F;
|
|
if (!events)
|
|
return;
|
|
|
|
irq_num = VIA2_SOURCE_BASE;
|
|
irq_bit = 1;
|
|
do {
|
|
if (events & irq_bit) {
|
|
via2[gIFR] = irq_bit | rbv_clear;
|
|
generic_handle_irq(irq_num);
|
|
}
|
|
++irq_num;
|
|
irq_bit <<= 1;
|
|
} while (events >= irq_bit);
|
|
}
|
|
|
|
/*
|
|
* Dispatch Nubus interrupts. We are called as a secondary dispatch by the
|
|
* VIA2 dispatcher as a fast interrupt handler.
|
|
*/
|
|
|
|
static void via_nubus_irq(struct irq_desc *desc)
|
|
{
|
|
int slot_irq;
|
|
unsigned char slot_bit, events;
|
|
|
|
events = ~via2[gBufA] & 0x7F;
|
|
if (rbv_present)
|
|
events &= via2[rSIER];
|
|
else
|
|
events &= ~via2[vDirA];
|
|
if (!events)
|
|
return;
|
|
|
|
do {
|
|
slot_irq = IRQ_NUBUS_F;
|
|
slot_bit = 0x40;
|
|
do {
|
|
if (events & slot_bit) {
|
|
events &= ~slot_bit;
|
|
generic_handle_irq(slot_irq);
|
|
}
|
|
--slot_irq;
|
|
slot_bit >>= 1;
|
|
} while (events);
|
|
|
|
/* clear the CA1 interrupt and make certain there's no more. */
|
|
via2[gIFR] = 0x02 | rbv_clear;
|
|
events = ~via2[gBufA] & 0x7F;
|
|
if (rbv_present)
|
|
events &= via2[rSIER];
|
|
else
|
|
events &= ~via2[vDirA];
|
|
} while (events);
|
|
}
|
|
|
|
/*
|
|
* Register the interrupt dispatchers for VIA or RBV machines only.
|
|
*/
|
|
|
|
void __init via_register_interrupts(void)
|
|
{
|
|
if (via_alt_mapping) {
|
|
/* software interrupt */
|
|
irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
|
|
/* via1 interrupt */
|
|
irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
|
|
} else {
|
|
irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
|
|
}
|
|
irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
|
|
irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
|
|
}
|
|
|
|
void via_irq_enable(int irq) {
|
|
int irq_src = IRQ_SRC(irq);
|
|
int irq_idx = IRQ_IDX(irq);
|
|
|
|
if (irq_src == 1) {
|
|
via1[vIER] = IER_SET_BIT(irq_idx);
|
|
} else if (irq_src == 2) {
|
|
if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
|
|
via2[gIER] = IER_SET_BIT(irq_idx);
|
|
} else if (irq_src == 7) {
|
|
switch (macintosh_config->via_type) {
|
|
case MAC_VIA_II:
|
|
case MAC_VIA_QUADRA:
|
|
nubus_disabled &= ~(1 << irq_idx);
|
|
/* Enable the CA1 interrupt when no slot is disabled. */
|
|
if (!nubus_disabled)
|
|
via2[gIER] = IER_SET_BIT(1);
|
|
break;
|
|
case MAC_VIA_IICI:
|
|
/* On RBV, enable the slot interrupt.
|
|
* SIER works like IER.
|
|
*/
|
|
via2[rSIER] = IER_SET_BIT(irq_idx);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
void via_irq_disable(int irq) {
|
|
int irq_src = IRQ_SRC(irq);
|
|
int irq_idx = IRQ_IDX(irq);
|
|
|
|
if (irq_src == 1) {
|
|
via1[vIER] = IER_CLR_BIT(irq_idx);
|
|
} else if (irq_src == 2) {
|
|
via2[gIER] = IER_CLR_BIT(irq_idx);
|
|
} else if (irq_src == 7) {
|
|
switch (macintosh_config->via_type) {
|
|
case MAC_VIA_II:
|
|
case MAC_VIA_QUADRA:
|
|
nubus_disabled |= 1 << irq_idx;
|
|
if (nubus_disabled)
|
|
via2[gIER] = IER_CLR_BIT(1);
|
|
break;
|
|
case MAC_VIA_IICI:
|
|
via2[rSIER] = IER_CLR_BIT(irq_idx);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
void via1_set_head(int head)
|
|
{
|
|
if (head == 0)
|
|
via1[vBufA] &= ~VIA1A_vHeadSel;
|
|
else
|
|
via1[vBufA] |= VIA1A_vHeadSel;
|
|
}
|
|
EXPORT_SYMBOL(via1_set_head);
|
|
|
|
int via2_scsi_drq_pending(void)
|
|
{
|
|
return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
|
|
}
|
|
EXPORT_SYMBOL(via2_scsi_drq_pending);
|
|
|
|
/* timer and clock source */
|
|
|
|
#define VIA_CLOCK_FREQ 783360 /* VIA "phase 2" clock in Hz */
|
|
#define VIA_TIMER_CYCLES (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */
|
|
|
|
#define VIA_TC (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */
|
|
#define VIA_TC_LOW (VIA_TC & 0xFF)
|
|
#define VIA_TC_HIGH (VIA_TC >> 8)
|
|
|
|
static u64 mac_read_clk(struct clocksource *cs);
|
|
|
|
static struct clocksource mac_clk = {
|
|
.name = "via1",
|
|
.rating = 250,
|
|
.read = mac_read_clk,
|
|
.mask = CLOCKSOURCE_MASK(32),
|
|
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
|
|
};
|
|
|
|
static u32 clk_total, clk_offset;
|
|
|
|
static irqreturn_t via_timer_handler(int irq, void *dev_id)
|
|
{
|
|
irq_handler_t timer_routine = dev_id;
|
|
|
|
clk_total += VIA_TIMER_CYCLES;
|
|
clk_offset = 0;
|
|
timer_routine(0, NULL);
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
void __init via_init_clock(irq_handler_t timer_routine)
|
|
{
|
|
if (request_irq(IRQ_MAC_TIMER_1, via_timer_handler, IRQF_TIMER, "timer",
|
|
timer_routine)) {
|
|
pr_err("Couldn't register %s interrupt\n", "timer");
|
|
return;
|
|
}
|
|
|
|
via1[vT1LL] = VIA_TC_LOW;
|
|
via1[vT1LH] = VIA_TC_HIGH;
|
|
via1[vT1CL] = VIA_TC_LOW;
|
|
via1[vT1CH] = VIA_TC_HIGH;
|
|
via1[vACR] |= 0x40;
|
|
|
|
clocksource_register_hz(&mac_clk, VIA_CLOCK_FREQ);
|
|
}
|
|
|
|
static u64 mac_read_clk(struct clocksource *cs)
|
|
{
|
|
unsigned long flags;
|
|
u8 count_high;
|
|
u16 count;
|
|
u32 ticks;
|
|
|
|
/*
|
|
* Timer counter wrap-around is detected with the timer interrupt flag
|
|
* but reading the counter low byte (vT1CL) would reset the flag.
|
|
* Also, accessing both counter registers is essentially a data race.
|
|
* These problems are avoided by ignoring the low byte. Clock accuracy
|
|
* is 256 times worse (error can reach 0.327 ms) but CPU overhead is
|
|
* reduced by avoiding slow VIA register accesses.
|
|
*/
|
|
|
|
local_irq_save(flags);
|
|
count_high = via1[vT1CH];
|
|
if (count_high == 0xFF)
|
|
count_high = 0;
|
|
if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
|
|
clk_offset = VIA_TIMER_CYCLES;
|
|
count = count_high << 8;
|
|
ticks = VIA_TIMER_CYCLES - count;
|
|
ticks += clk_offset + clk_total;
|
|
local_irq_restore(flags);
|
|
|
|
return ticks;
|
|
}
|