* [PATCH v2 1/2] hw/openrisc/openrisc_sim: keep serial@90000000 as default
2024-12-01 7:09 [PATCH v2 0/2] Misc OpenRISC fixes for 9.2.0 Stafford Horne
@ 2024-12-01 7:09 ` Stafford Horne
2024-12-02 16:59 ` Peter Maydell
2024-12-01 7:09 ` [PATCH v2 2/2] hw/openrisc: Fixed undercounting of TTCR in continuous mode Stafford Horne
2024-12-02 16:54 ` [PATCH v2 0/2] Misc OpenRISC fixes for 9.2.0 Peter Maydell
2 siblings, 1 reply; 6+ messages in thread
From: Stafford Horne @ 2024-12-01 7:09 UTC (permalink / raw)
To: QEMU Development; +Cc: Ahmad Fatoum, qemu-stable, Stafford Horne, Jia Liu
From: Ahmad Fatoum <a.fatoum@pengutronix.de>
We used to only have a single UART on the platform and it was located at
address 0x90000000. When the number of UARTs was increased to 4, the
first UART remained at it's location, but instead of being the first one
to be registered, it became the last.
This caused QEMU to pick 0x90000300 as the default UART, which broke
software that hardcoded the address of 0x90000000 and expected it's
output to be visible when the user configured only a single console.
This caused regressions[1] in the barebox test suite when updating to a
newer QEMU. As there seems to be no good reason to register the UARTs in
inverse order, let's register them by ascending address, so existing
software can remain oblivious to the additional UART ports.
Changing the order of uart registration alone breaks Linux which
was choosing the UART at 0x90000300 as the default for ttyS0. To fix
Linux we fix two things in the device tree:
1. Define stdout-path only one time for the first registered UART
instead of incorrectly defining for each UART.
2. Change the UART alias name from 'uart0' to 'serial0' as almost all
Linux tty drivers look for an alias starting with "serial".
[1]: https://lore.barebox.org/barebox/707e7c50-aad1-4459-8796-0cc54bab32e2@pengutronix.de/T/#m5da26e8a799033301489a938b5d5667b81cef6ad
Fixes: 777784bda468 ("hw/openrisc: support 4 serial ports in or1ksim")
Cc: qemu-stable@nongnu.org
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
[stafford: Change to serial0 alias and update change message, reverse
uart registration order]
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
Since v1:
- Fix commit message and reverse registration order as pointed out by Peter.
hw/openrisc/openrisc_sim.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/hw/openrisc/openrisc_sim.c b/hw/openrisc/openrisc_sim.c
index 9fb63515ef..42f002985b 100644
--- a/hw/openrisc/openrisc_sim.c
+++ b/hw/openrisc/openrisc_sim.c
@@ -250,7 +250,7 @@ static void openrisc_sim_serial_init(Or1ksimState *state, hwaddr base,
void *fdt = state->fdt;
char *nodename;
qemu_irq serial_irq;
- char alias[sizeof("uart0")];
+ char alias[sizeof("serial0")];
int i;
if (num_cpus > 1) {
@@ -265,7 +265,7 @@ static void openrisc_sim_serial_init(Or1ksimState *state, hwaddr base,
serial_irq = get_cpu_irq(cpus, 0, irq_pin);
}
serial_mm_init(get_system_memory(), base, 0, serial_irq, 115200,
- serial_hd(OR1KSIM_UART_COUNT - uart_idx - 1),
+ serial_hd(uart_idx),
DEVICE_NATIVE_ENDIAN);
/* Add device tree node for serial. */
@@ -277,10 +277,13 @@ static void openrisc_sim_serial_init(Or1ksimState *state, hwaddr base,
qemu_fdt_setprop_cell(fdt, nodename, "clock-frequency", OR1KSIM_CLK_MHZ);
qemu_fdt_setprop(fdt, nodename, "big-endian", NULL, 0);
- /* The /chosen node is created during fdt creation. */
- qemu_fdt_setprop_string(fdt, "/chosen", "stdout-path", nodename);
- snprintf(alias, sizeof(alias), "uart%d", uart_idx);
+ if (uart_idx == 0) {
+ /* The /chosen node is created during fdt creation. */
+ qemu_fdt_setprop_string(fdt, "/chosen", "stdout-path", nodename);
+ }
+ snprintf(alias, sizeof(alias), "serial%d", uart_idx);
qemu_fdt_setprop_string(fdt, "/aliases", alias, nodename);
+
g_free(nodename);
}
@@ -326,11 +329,22 @@ static void openrisc_sim_init(MachineState *machine)
smp_cpus, cpus, OR1KSIM_OMPIC_IRQ);
}
- for (n = 0; n < OR1KSIM_UART_COUNT; ++n)
+ /*
+ * We create the UART nodes starting with the highest address and
+ * working downwards, because in QEMU the DTB nodes end up in the
+ * DTB in reverse order of creation. Correctly-written guest software
+ * will not care about the node order (it will look at stdout-path
+ * or the alias nodes), but for the benefit of guest software which
+ * just looks for the first UART node in the DTB, make sure the
+ * lowest-address UART (which is QEMU's first serial port) appears
+ * first in the DTB.
+ */
+ for (n = OR1KSIM_UART_COUNT - 1; n >= 0; n--) {
openrisc_sim_serial_init(state, or1ksim_memmap[OR1KSIM_UART].base +
or1ksim_memmap[OR1KSIM_UART].size * n,
or1ksim_memmap[OR1KSIM_UART].size,
smp_cpus, cpus, OR1KSIM_UART_IRQ, n);
+ }
load_addr = openrisc_load_kernel(ram_size, kernel_filename,
&boot_info.bootstrap_pc);
--
2.47.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v2 2/2] hw/openrisc: Fixed undercounting of TTCR in continuous mode
2024-12-01 7:09 [PATCH v2 0/2] Misc OpenRISC fixes for 9.2.0 Stafford Horne
2024-12-01 7:09 ` [PATCH v2 1/2] hw/openrisc/openrisc_sim: keep serial@90000000 as default Stafford Horne
@ 2024-12-01 7:09 ` Stafford Horne
2024-12-02 16:54 ` [PATCH v2 0/2] Misc OpenRISC fixes for 9.2.0 Peter Maydell
2 siblings, 0 replies; 6+ messages in thread
From: Stafford Horne @ 2024-12-01 7:09 UTC (permalink / raw)
To: QEMU Development; +Cc: Joel Holdsworth, Stafford Horne
From: Joel Holdsworth <jholdsworth@nvidia.com>
In the existing design, TTCR is prone to undercounting when running in
continuous mode. This manifests as a timer interrupt appearing to
trigger a few cycles prior to the deadline set in SPR_TTMR_TP.
When the timer triggers, the virtual time delta in nanoseconds between
the time when the timer was set, and when it triggers is calculated.
This nanoseconds value is then divided by TIMER_PERIOD (50) to compute
an increment of cycles to apply to TTCR.
However, this calculation rounds down the number of cycles causing the
undercounting.
A simplistic solution would be to instead round up the number of cycles,
however this will result in the accumulation of timing error over time.
This patch corrects the issue by calculating the time delta in
nanoseconds between when the timer was last reset and the timer event.
This approach allows the TTCR value to be rounded up, but without
accumulating error over time.
Signed-off-by: Joel Holdsworth <jholdsworth@nvidia.com>
[stafford: Incremented version in vmstate_or1k_timer, checkpatch fixes]
Signed-off-by: Stafford Horne <shorne@gmail.com>
---
Since v1:
- Use DIVIDE_ROUND_UP instead of open coding as pointed out by Richard
- Fix off-by-1 bug in TTCR patch pointed out by Richard
hw/openrisc/cputimer.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)
diff --git a/hw/openrisc/cputimer.c b/hw/openrisc/cputimer.c
index 835986c4db..87aa353323 100644
--- a/hw/openrisc/cputimer.c
+++ b/hw/openrisc/cputimer.c
@@ -29,7 +29,8 @@
/* Tick Timer global state to allow all cores to be in sync */
typedef struct OR1KTimerState {
uint32_t ttcr;
- uint64_t last_clk;
+ uint32_t ttcr_offset;
+ uint64_t clk_offset;
} OR1KTimerState;
static OR1KTimerState *or1k_timer;
@@ -37,6 +38,8 @@ static OR1KTimerState *or1k_timer;
void cpu_openrisc_count_set(OpenRISCCPU *cpu, uint32_t val)
{
or1k_timer->ttcr = val;
+ or1k_timer->ttcr_offset = val;
+ or1k_timer->clk_offset = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
}
uint32_t cpu_openrisc_count_get(OpenRISCCPU *cpu)
@@ -53,9 +56,8 @@ void cpu_openrisc_count_update(OpenRISCCPU *cpu)
return;
}
now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
- or1k_timer->ttcr += (uint32_t)((now - or1k_timer->last_clk)
- / TIMER_PERIOD);
- or1k_timer->last_clk = now;
+ or1k_timer->ttcr = or1k_timer->ttcr_offset +
+ DIV_ROUND_UP(now - or1k_timer->clk_offset, TIMER_PERIOD);
}
/* Update the next timeout time as difference between ttmr and ttcr */
@@ -69,7 +71,7 @@ void cpu_openrisc_timer_update(OpenRISCCPU *cpu)
}
cpu_openrisc_count_update(cpu);
- now = or1k_timer->last_clk;
+ now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
if ((cpu->env.ttmr & TTMR_TP) <= (or1k_timer->ttcr & TTMR_TP)) {
wait = TTMR_TP - (or1k_timer->ttcr & TTMR_TP) + 1;
@@ -110,7 +112,8 @@ static void openrisc_timer_cb(void *opaque)
case TIMER_NONE:
break;
case TIMER_INTR:
- or1k_timer->ttcr = 0;
+ /* Zero the count by applying a negative offset to the counter */
+ or1k_timer->ttcr_offset -= (cpu->env.ttmr & TTMR_TP);
break;
case TIMER_SHOT:
cpu_openrisc_count_stop(cpu);
@@ -137,17 +140,18 @@ static void openrisc_count_reset(void *opaque)
/* Reset the global timer state. */
static void openrisc_timer_reset(void *opaque)
{
- or1k_timer->ttcr = 0x00000000;
- or1k_timer->last_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+ OpenRISCCPU *cpu = opaque;
+ cpu_openrisc_count_set(cpu, 0);
}
static const VMStateDescription vmstate_or1k_timer = {
.name = "or1k_timer",
- .version_id = 1,
- .minimum_version_id = 1,
+ .version_id = 2,
+ .minimum_version_id = 2,
.fields = (const VMStateField[]) {
VMSTATE_UINT32(ttcr, OR1KTimerState),
- VMSTATE_UINT64(last_clk, OR1KTimerState),
+ VMSTATE_UINT32(ttcr_offset, OR1KTimerState),
+ VMSTATE_UINT64(clk_offset, OR1KTimerState),
VMSTATE_END_OF_LIST()
}
};
--
2.47.0
^ permalink raw reply related [flat|nested] 6+ messages in thread