From 940aabb9f47712da87182fee7163f1d3f7def36d Mon Sep 17 00:00:00 2001
From: Alistair Francis <alistair.francis@wdc.com>
Date: Thu, 9 Jul 2020 15:04:48 -0700
Subject: [PATCH] hw/char: Convert the Ibex UART to use the qdev Clock model
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Conver the Ibex UART to use the recently added qdev-clock functions.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: b0136fad870a29049959ec161c1217b967d7e19d.1594332223.git.alistair.francis@wdc.com
Message-Id: <b0136fad870a29049959ec161c1217b967d7e19d.1594332223.git.alistair.francis@wdc.com>
---
 hw/char/ibex_uart.c         | 30 +++++++++++++++++++++++++++---
 include/hw/char/ibex_uart.h |  3 +++
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/hw/char/ibex_uart.c b/hw/char/ibex_uart.c
index 45cd724998..ab6247de89 100644
--- a/hw/char/ibex_uart.c
+++ b/hw/char/ibex_uart.c
@@ -28,6 +28,7 @@
 #include "qemu/osdep.h"
 #include "hw/char/ibex_uart.h"
 #include "hw/irq.h"
+#include "hw/qdev-clock.h"
 #include "hw/qdev-properties.h"
 #include "migration/vmstate.h"
 #include "qemu/log.h"
@@ -203,6 +204,17 @@ static void ibex_uart_reset(DeviceState *dev)
     ibex_uart_update_irqs(s);
 }
 
+static uint64_t ibex_uart_get_baud(IbexUartState *s)
+{
+    uint64_t baud;
+
+    baud = ((s->uart_ctrl & UART_CTRL_NCO) >> 16);
+    baud *= clock_get_hz(s->f_clk);
+    baud >>= 20;
+
+    return baud;
+}
+
 static uint64_t ibex_uart_read(void *opaque, hwaddr addr,
                                        unsigned int size)
 {
@@ -329,9 +341,7 @@ static void ibex_uart_write(void *opaque, hwaddr addr,
                           "%s: UART_CTRL_RXBLVL is not supported\n", __func__);
         }
         if (value & UART_CTRL_NCO) {
-            uint64_t baud = ((value & UART_CTRL_NCO) >> 16);
-            baud *= 1000;
-            baud >>= 20;
+            uint64_t baud = ibex_uart_get_baud(s);
 
             s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10;
         }
@@ -385,6 +395,16 @@ static void ibex_uart_write(void *opaque, hwaddr addr,
     }
 }
 
+static void ibex_uart_clk_update(void *opaque)
+{
+    IbexUartState *s = opaque;
+
+    /* recompute uart's speed on clock change */
+    uint64_t baud = ibex_uart_get_baud(s);
+
+    s->char_tx_time = (NANOSECONDS_PER_SECOND / baud) * 10;
+}
+
 static void fifo_trigger_update(void *opaque)
 {
     IbexUartState *s = opaque;
@@ -444,6 +464,10 @@ static void ibex_uart_init(Object *obj)
 {
     IbexUartState *s = IBEX_UART(obj);
 
+    s->f_clk = qdev_init_clock_in(DEVICE(obj), "f_clock",
+                                  ibex_uart_clk_update, s);
+    clock_set_hz(s->f_clk, IBEX_UART_CLOCK);
+
     sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_watermark);
     sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->rx_watermark);
     sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->tx_empty);
diff --git a/include/hw/char/ibex_uart.h b/include/hw/char/ibex_uart.h
index 2bec772615..6d81051161 100644
--- a/include/hw/char/ibex_uart.h
+++ b/include/hw/char/ibex_uart.h
@@ -72,6 +72,7 @@
 #define IBEX_UART_TIMEOUT_CTRL 0x2c
 
 #define IBEX_UART_TX_FIFO_SIZE 16
+#define IBEX_UART_CLOCK 50000000 /* 50MHz clock */
 
 #define TYPE_IBEX_UART "ibex-uart"
 #define IBEX_UART(obj) \
@@ -101,6 +102,8 @@ typedef struct {
     uint32_t uart_val;
     uint32_t uart_timeout_ctrl;
 
+    Clock *f_clk;
+
     CharBackend chr;
     qemu_irq tx_watermark;
     qemu_irq rx_watermark;