Patchwork serial: Add interface to set reference oscillator frequency

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Submitter Stefan Weil
Date Oct. 31, 2009, 10:28 a.m.
Message ID <1256984891-21014-1-git-send-email-weil@mail.berlios.de>
Download mbox | patch
Permalink /patch/37359/
State New
Headers show

Comments

Stefan Weil - Oct. 31, 2009, 10:28 a.m.
Many (most?) serial interfaces have a programmable
clock which provides the reference frequency ("baudbase").
So a fixed baudbase which is only set once can be wrong.

omap1.c is an example which could use the new interface
to change baudbase when the programmable clock changes.
ar7 system emulation (still not part of standard QEMU)
is similar to omap and already uses serial_set_frequency.

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
---
 hw/pc.h     |    1 +
 hw/serial.c |    7 +++++++
 2 files changed, 8 insertions(+), 0 deletions(-)

Patch

diff --git a/hw/pc.h b/hw/pc.h
index 15fff8d..03ffc91 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -13,6 +13,7 @@  SerialState *serial_mm_init (target_phys_addr_t base, int it_shift,
                              qemu_irq irq, int baudbase,
                              CharDriverState *chr, int ioregister);
 SerialState *serial_isa_init(int index, CharDriverState *chr);
+void serial_set_frequency(SerialState *s, uint32_t frequency);
 
 /* parallel.c */
 
diff --git a/hw/serial.c b/hw/serial.c
index 9353201..754727f 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -731,6 +731,13 @@  static void serial_init_core(SerialState *s)
                           serial_event, s);
 }
 
+/* Change the main reference oscillator frequency. */
+void serial_set_frequency(SerialState *s, uint32_t frequency)
+{
+    s->baudbase = frequency;
+    serial_update_parameters(s);
+}
+
 static const int isa_serial_io[MAX_SERIAL_PORTS] = { 0x3f8, 0x2f8, 0x3e8, 0x2e8 };
 static const int isa_serial_irq[MAX_SERIAL_PORTS] = { 4, 3, 4, 3 };