Re: [Qemu-devel] [PATCH 1/1] add output register property and update the

["Zhou Yuan" <zhouyuan.fnst@cn.fujitsu.com>]

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From: Zhouy <zhouyuan.fnst@cn.fujitsu.com>
To: qemu-devel@nongnu.org
Date: Tue, 15 Oct 2013 15:20:47 -0400
Subject: Re: [PATCH 1/1] add output register property and update the
 outputports level when necessary

I found some instruction of output port register in the datasheet:
" Reads from the output port register reflect the value that is in the flip-flop
controlling the output selection, not the actual I/O value, which may differ if
the out-put is overloaded."
So the level of output pins should be updated according to the "Output Register"
when “Configuration Register" is writen. 

> qemu-master/hw/gpio/max7310.c |   33 ++++++++++++++++++++++-----------
> 1 files changed, 22 insertions(+), 11 deletions(-)
>
>diff --git a/qemu-master/hw/gpio/max7310.c b/qemu-master/hw/gpio/max7310.c
>index 59b2877..ffbeb6f 100644
>--- a/qemu-master/hw/gpio/max7310.c
>+++ b/qemu-master/hw/gpio/max7310.c
>@@ -19,10 +19,25 @@ typedef struct {
>     uint8_t polarity;
>     uint8_t status;
>     uint8_t command;
>+    uint8_t output;
>     qemu_irq handler[8];
>     qemu_irq *gpio_in;
> } MAX7310State;
> 
>+/*this function to update outputports level*/
>+static void max7310_update(MAX7310State *s)
>+{
>+    uint8_t diff = 0;
>+    uint8_t line = 0;
>+    for (diff = (s->output ^ s->level) & ~s->direction; diff;
>+                diff &= ~(1 << line)) {
>+        line = ffs(diff) - 1;
>+        if (s->handler[line]) {
>+            qemu_set_irq(s->handler[line], (s->output >> line) & 1);
>+        }
>+    }
>+    s->level = (s->level & s->direction) | (s->level & ~s->direction);
>+}
>+
> static void max7310_reset(DeviceState *dev)
> {
>     MAX7310State *s = FROM_I2C_SLAVE(MAX7310State, I2C_SLAVE(dev));
>@@ -31,6 +46,8 @@ static void max7310_reset(DeviceState *dev)
>     s->polarity = 0xf0;
>     s->status = 0x01;
>     s->command = 0x00;
>+    s->output = 0x00;
>+    max7310_update(s);
> }
> 
> static int max7310_rx(I2CSlave *i2c)
>@@ -43,7 +60,7 @@ static int max7310_rx(I2CSlave *i2c)
>         break;
> 
>     case 0x01:	/* Output port */
>-        return s->level & ~s->direction;
>+        return s->output;
>         break;
> 
>     case 0x02:	/* Polarity inversion */
>@@ -71,8 +88,6 @@ static int max7310_rx(I2CSlave *i2c)
> static int max7310_tx(I2CSlave *i2c, uint8_t data)
> {
>     MAX7310State *s = (MAX7310State *) i2c;
>-    uint8_t diff;
>-    int line;
> 
>     if (s->len ++ > 1) {
> #ifdef VERBOSE
>@@ -89,13 +104,8 @@ static int max7310_tx(I2CSlave *i2c, uint8_t data)
> 
>     switch (s->command) {
>     case 0x01:	/* Output port */
>-        for (diff = (data ^ s->level) & ~s->direction; diff;
>-                        diff &= ~(1 << line)) {
>-            line = ffs(diff) - 1;
>-            if (s->handler[line])
>-                qemu_set_irq(s->handler[line], (data >> line) & 1);
>-        }
>-        s->level = (s->level & s->direction) | (data & ~s->direction);
>+        s->output = data;
>+        max7310_update(s);
>         break;
> 
>     case 0x02:	/* Polarity inversion */
>@@ -103,8 +113,8 @@ static int max7310_tx(I2CSlave *i2c, uint8_t data)
>         break;
> 
>     case 0x03:	/* Configuration */
>-        s->level &= ~(s->direction ^ data);
>         s->direction = data;
>+        max7310_update(s);
>         break;
> 
>     case 0x04:	/* Timeout */
>@@ -156,6 +166,7 @@ static const VMStateDescription vmstate_max7310 = {
>         VMSTATE_UINT8(polarity, MAX7310State),
>         VMSTATE_UINT8(status, MAX7310State),
>         VMSTATE_UINT8(command, MAX7310State),
>+        VMSTATE_UINT8(output, MAX7310State),
>         VMSTATE_I2C_SLAVE(i2c, MAX7310State),
>         VMSTATE_END_OF_LIST()
>     }
>-- 
>1.7.6
Ping,anyone?


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--------------------------------------------------
Zhou Yuan
Nanjing Fujitsu Nanda Software Tech. Co., Ltd.(FNST)
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zhouyuan.fnst@cn.fujitsu.com
15:14:50