From 424f79f35a94611f73182f19a7711174b756b052 Mon Sep 17 00:00:00 2001
From: P33M <P33M@github.com>
Date: Fri, 26 Sep 2014 11:32:09 +0100
Subject: [PATCH 092/114] dwc_otg: introduce fiq_fsm_spin(un|)lock()
SMP safety for the FIQ relies on register read-modify write cycles being
completed in the correct order. Several places in the DWC code modify
registers also touched by the FIQ. Protect these by a bare-bones lock
mechanism.
This also makes it possible to run the FIQ and IRQ handlers on different
cores.
---
.../usb/host/dwc_common_port/dwc_common_linux.c | 6 ---
drivers/usb/host/dwc_otg/dwc_otg_cil.c | 10 -----
drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.c | 46 +++++++++++++++++++++-
drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.h | 16 +++++++-
drivers/usb/host/dwc_otg/dwc_otg_hcd.c | 23 ++++++++++-
drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c | 9 ++++-
6 files changed, 88 insertions(+), 22 deletions(-)
--- a/drivers/usb/host/dwc_common_port/dwc_common_linux.c
+++ b/drivers/usb/host/dwc_common_port/dwc_common_linux.c
@@ -580,13 +580,7 @@ void DWC_WRITE_REG64(uint64_t volatile *
void DWC_MODIFY_REG32(uint32_t volatile *reg, uint32_t clear_mask, uint32_t set_mask)
{
- unsigned long flags;
-
- local_irq_save(flags);
- local_fiq_disable();
writel((readl(reg) & ~clear_mask) | set_mask, reg);
- local_fiq_enable();
- local_irq_restore(flags);
}
#if 0
--- a/drivers/usb/host/dwc_otg/dwc_otg_cil.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_cil.c
@@ -2244,9 +2244,7 @@ void dwc_otg_core_host_init(dwc_otg_core
*/
void dwc_otg_hc_init(dwc_otg_core_if_t * core_if, dwc_hc_t * hc)
{
- uint32_t intr_enable;
hcintmsk_data_t hc_intr_mask;
- gintmsk_data_t gintmsk = {.d32 = 0 };
hcchar_data_t hcchar;
hcsplt_data_t hcsplt;
@@ -2348,14 +2346,6 @@ void dwc_otg_hc_init(dwc_otg_core_if_t *
}
DWC_WRITE_REG32(&hc_regs->hcintmsk, hc_intr_mask.d32);
- /* Enable the top level host channel interrupt. */
- intr_enable = (1 << hc_num);
- DWC_MODIFY_REG32(&host_if->host_global_regs->haintmsk, 0, intr_enable);
-
- /* Make sure host channel interrupts are enabled. */
- gintmsk.b.hcintr = 1;
- DWC_MODIFY_REG32(&core_if->core_global_regs->gintmsk, 0, gintmsk.d32);
-
/*
* Program the HCCHARn register with the endpoint characteristics for
* the current transfer.
--- a/drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.c
@@ -75,6 +75,46 @@ void notrace _fiq_print(enum fiq_debug_l
}
/**
+ * fiq_fsm_spin_lock() - ARMv6+ bare bones spinlock
+ * Must be called with local interrupts and FIQ disabled.
+ */
+inline void fiq_fsm_spin_lock(fiq_lock_t *lock)
+{
+ unsigned long tmp;
+ uint32_t newval;
+ fiq_lock_t lockval;
+ smp_mb__before_spinlock();
+ /* Nested locking, yay. If we are on the same CPU as the fiq, then the disable
+ * will be sufficient. If we are on a different CPU, then the lock protects us. */
+ prefetchw(&lock->slock);
+ asm volatile (
+ "1: ldrex %0, [%3]\n"
+ " add %1, %0, %4\n"
+ " strex %2, %1, [%3]\n"
+ " teq %2, #0\n"
+ " bne 1b"
+ : "=&r" (lockval), "=&r" (newval), "=&r" (tmp)
+ : "r" (&lock->slock), "I" (1 << 16)
+ : "cc");
+
+ while (lockval.tickets.next != lockval.tickets.owner) {
+ wfe();
+ lockval.tickets.owner = ACCESS_ONCE(lock->tickets.owner);
+ }
+ smp_mb();
+}
+
+/**
+ * fiq_fsm_spin_unlock() - ARMv6+ bare bones spinunlock
+ */
+inline void fiq_fsm_spin_unlock(fiq_lock_t *lock)
+{
+ smp_mb();
+ lock->tickets.owner++;
+ dsb_sev();
+}
+
+/**
* fiq_fsm_restart_channel() - Poke channel enable bit for a split transaction
* @channel: channel to re-enable
*/
@@ -1142,6 +1182,7 @@ void notrace dwc_otg_fiq_fsm(struct fiq_
gintsts_handled.d32 = 0;
haint_handled.d32 = 0;
+ fiq_fsm_spin_lock(&state->lock);
gintsts.d32 = FIQ_READ(state->dwc_regs_base + GINTSTS);
gintmsk.d32 = FIQ_READ(state->dwc_regs_base + GINTMSK);
gintsts.d32 &= gintmsk.d32;
@@ -1231,7 +1272,7 @@ void notrace dwc_otg_fiq_fsm(struct fiq_
}
state->fiq_done++;
- mb();
+ fiq_fsm_spin_unlock(&state->lock);
}
@@ -1253,6 +1294,7 @@ void notrace dwc_otg_fiq_nop(struct fiq_
gintmsk_data_t gintmsk;
hfnum_data_t hfnum;
+ fiq_fsm_spin_lock(&state->lock);
hfnum.d32 = FIQ_READ(state->dwc_regs_base + HFNUM);
gintsts.d32 = FIQ_READ(state->dwc_regs_base + GINTSTS);
gintmsk.d32 = FIQ_READ(state->dwc_regs_base + GINTMSK);
@@ -1290,5 +1332,5 @@ void notrace dwc_otg_fiq_nop(struct fiq_
}
state->fiq_done++;
- mb();
+ fiq_fsm_spin_unlock(&state->lock);
}
--- a/drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.h
+++ b/drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.h
@@ -120,7 +120,6 @@ typedef struct {
volatile void* intstat;
} mphi_regs_t;
-
enum fiq_debug_level {
FIQDBG_SCHED = (1 << 0),
FIQDBG_INT = (1 << 1),
@@ -128,6 +127,16 @@ enum fiq_debug_level {
FIQDBG_PORTHUB = (1 << 3),
};
+typedef struct {
+ union {
+ uint32_t slock;
+ struct _tickets {
+ uint16_t owner;
+ uint16_t next;
+ } tickets;
+ };
+} fiq_lock_t;
+
struct fiq_state;
extern void _fiq_print (enum fiq_debug_level dbg_lvl, volatile struct fiq_state *state, char *fmt, ...);
@@ -324,6 +333,7 @@ struct fiq_channel_state {
* It contains top-level state information.
*/
struct fiq_state {
+ fiq_lock_t lock;
mphi_regs_t mphi_regs;
void *dwc_regs_base;
dma_addr_t dma_base;
@@ -342,6 +352,10 @@ struct fiq_state {
struct fiq_channel_state channel[0];
};
+extern void fiq_fsm_spin_lock(fiq_lock_t *lock);
+
+extern void fiq_fsm_spin_unlock(fiq_lock_t *lock);
+
extern int fiq_fsm_too_late(struct fiq_state *st, int n);
extern int fiq_fsm_tt_in_use(struct fiq_state *st, int num_channels, int n);
--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
@@ -1184,6 +1184,9 @@ static void assign_and_init_hc(dwc_otg_h
dwc_otg_qtd_t *qtd;
dwc_otg_hcd_urb_t *urb;
void* ptr = NULL;
+ uint32_t intr_enable;
+ unsigned long flags;
+ gintmsk_data_t gintmsk = { .d32 = 0, };
qtd = DWC_CIRCLEQ_FIRST(&qh->qtd_list);
@@ -1409,6 +1412,20 @@ static void assign_and_init_hc(dwc_otg_h
hc->desc_list_addr = qh->desc_list_dma;
dwc_otg_hc_init(hcd->core_if, hc);
+
+ local_irq_save(flags);
+ local_fiq_disable();
+ fiq_fsm_spin_lock(&hcd->fiq_state->lock);
+ /* Enable the top level host channel interrupt. */
+ intr_enable = (1 << hc->hc_num);
+ DWC_MODIFY_REG32(&hcd->core_if->host_if->host_global_regs->haintmsk, 0, intr_enable);
+
+ /* Make sure host channel interrupts are enabled. */
+ gintmsk.b.hcintr = 1;
+ DWC_MODIFY_REG32(&hcd->core_if->core_global_regs->gintmsk, 0, gintmsk.d32);
+ fiq_fsm_spin_unlock(&hcd->fiq_state->lock);
+ local_fiq_enable();
+ local_irq_restore(flags);
hc->qh = qh;
}
@@ -1659,6 +1676,7 @@ int fiq_fsm_queue_isoc_transaction(dwc_o
fiq_print(FIQDBG_INT, hcd->fiq_state, "%08x", st->hcdma_copy.d32);
hfnum.d32 = DWC_READ_REG32(&hcd->core_if->host_if->host_global_regs->hfnum);
local_fiq_disable();
+ fiq_fsm_spin_lock(&hcd->fiq_state->lock);
DWC_WRITE_REG32(&hc_regs->hctsiz, st->hctsiz_copy.d32);
DWC_WRITE_REG32(&hc_regs->hcsplt, st->hcsplt_copy.d32);
DWC_WRITE_REG32(&hc_regs->hcdma, st->hcdma_copy.d32);
@@ -1676,6 +1694,7 @@ int fiq_fsm_queue_isoc_transaction(dwc_o
}
mb();
st->hcchar_copy.b.chen = 0;
+ fiq_fsm_spin_unlock(&hcd->fiq_state->lock);
local_fiq_enable();
return 0;
}
@@ -1811,7 +1830,7 @@ int fiq_fsm_queue_split_transaction(dwc_
DWC_WRITE_REG32(&hc_regs->hcintmsk, st->hcintmsk_copy.d32);
local_fiq_disable();
- mb();
+ fiq_fsm_spin_lock(&hcd->fiq_state->lock);
if (hc->ep_type & 0x1) {
hfnum.d32 = DWC_READ_REG32(&hcd->core_if->host_if->host_global_regs->hfnum);
@@ -1909,7 +1928,7 @@ int fiq_fsm_queue_split_transaction(dwc_
st->hcchar_copy.b.chen = 1;
DWC_WRITE_REG32(&hc_regs->hcchar, st->hcchar_copy.d32);
}
- mb();
+ fiq_fsm_spin_unlock(&hcd->fiq_state->lock);
local_fiq_enable();
return 0;
}
--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c
@@ -101,6 +101,7 @@ int32_t dwc_otg_hcd_handle_intr(dwc_otg_
if (dwc_otg_is_host_mode(core_if)) {
if (fiq_enable) {
local_fiq_disable();
+ fiq_fsm_spin_lock(&dwc_otg_hcd->fiq_state->lock);
/* Pull in from the FIQ's disabled mask */
gintmsk.d32 = gintmsk.d32 | ~(dwc_otg_hcd->fiq_state->gintmsk_saved.d32);
dwc_otg_hcd->fiq_state->gintmsk_saved.d32 = ~0;
@@ -116,8 +117,10 @@ int32_t dwc_otg_hcd_handle_intr(dwc_otg_
}
gintsts.d32 &= gintmsk.d32;
- if (fiq_enable)
+ if (fiq_enable) {
+ fiq_fsm_spin_unlock(&dwc_otg_hcd->fiq_state->lock);
local_fiq_enable();
+ }
if (!gintsts.d32) {
goto exit_handler_routine;
@@ -200,6 +203,7 @@ exit_handler_routine:
gintmsk_data_t gintmsk_new;
haintmsk_data_t haintmsk_new;
local_fiq_disable();
+ fiq_fsm_spin_lock(&dwc_otg_hcd->fiq_state->lock);
gintmsk_new.d32 = *(volatile uint32_t *)&dwc_otg_hcd->fiq_state->gintmsk_saved.d32;
if(fiq_fsm_enable)
haintmsk_new.d32 = *(volatile uint32_t *)&dwc_otg_hcd->fiq_state->haintmsk_saved.d32;
@@ -222,6 +226,7 @@ exit_handler_routine:
haintmsk.d32 = DWC_READ_REG32(&core_if->host_if->host_global_regs->haintmsk);
/* Re-enable interrupts that the FIQ masked (first time round) */
FIQ_WRITE(dwc_otg_hcd->fiq_state->dwc_regs_base + GINTMSK, gintmsk.d32);
+ fiq_fsm_spin_unlock(&dwc_otg_hcd->fiq_state->lock);
local_fiq_enable();
if ((jiffies / HZ) > last_time) {
@@ -633,8 +638,10 @@ int32_t dwc_otg_hcd_handle_hc_intr(dwc_o
{
/* check the mask? */
local_fiq_disable();
+ fiq_fsm_spin_lock(&dwc_otg_hcd->fiq_state->lock);
haint.b2.chint |= ~(dwc_otg_hcd->fiq_state->haintmsk_saved.b2.chint);
dwc_otg_hcd->fiq_state->haintmsk_saved.b2.chint = ~0;
+ fiq_fsm_spin_unlock(&dwc_otg_hcd->fiq_state->lock);
local_fiq_enable();
}