From: Klaus Jensen <its@irrelevant.dk>
To: qemu-devel@nongnu.org
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
"Arun Kumar Kashinath Agasar" <arun.kka@samsung.com>,
"Corey Minyard" <cminyard@mvista.com>,
"Andrew Jeffery" <andrew@aj.id.au>,
"Klaus Jensen" <k.jensen@samsung.com>,
"Cédric Le Goater" <clg@kaod.org>,
qemu-arm@nongnu.org, "Joel Stanley" <joel@jms.id.au>,
"Padmakar Kalghatgi" <p.kalghatgi@samsung.com>,
"Matt Johnston" <matt@codeconstruct.com.au>,
"Jeremy Kerr" <jk@ozlabs.org>
Subject: [RFC PATCH 1/4] hw/i2c: support multiple masters
Date: Thu, 31 Mar 2022 18:57:34 +0200 [thread overview]
Message-ID: <20220331165737.1073520-2-its@irrelevant.dk> (raw)
In-Reply-To: <20220331165737.1073520-1-its@irrelevant.dk>
From: Klaus Jensen <k.jensen@samsung.com>
Allow slaves to master the bus by registering a bottom halve. If the bus
is busy, the bottom halve is queued up. When a slave has succesfully
mastered the bus, the bottom halve is scheduled.
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
hw/i2c/core.c | 34 +++++++++++++++++++++++++++++++++-
include/hw/i2c/i2c.h | 14 ++++++++++++++
2 files changed, 47 insertions(+), 1 deletion(-)
diff --git a/hw/i2c/core.c b/hw/i2c/core.c
index d0cb2d32fa44..145dce60782a 100644
--- a/hw/i2c/core.c
+++ b/hw/i2c/core.c
@@ -13,6 +13,7 @@
#include "migration/vmstate.h"
#include "qapi/error.h"
#include "qemu/module.h"
+#include "qemu/main-loop.h"
#include "trace.h"
#define I2C_BROADCAST 0x00
@@ -62,6 +63,7 @@ I2CBus *i2c_init_bus(DeviceState *parent, const char *name)
bus = I2C_BUS(qbus_new(TYPE_I2C_BUS, parent, name));
QLIST_INIT(&bus->current_devs);
+ QSIMPLEQ_INIT(&bus->pending_masters);
vmstate_register(NULL, VMSTATE_INSTANCE_ID_ANY, &vmstate_i2c_bus, bus);
return bus;
}
@@ -74,7 +76,7 @@ void i2c_slave_set_address(I2CSlave *dev, uint8_t address)
/* Return nonzero if bus is busy. */
int i2c_bus_busy(I2CBus *bus)
{
- return !QLIST_EMPTY(&bus->current_devs);
+ return !QLIST_EMPTY(&bus->current_devs) || bus->bh;
}
bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
@@ -180,6 +182,26 @@ int i2c_start_transfer(I2CBus *bus, uint8_t address, bool is_recv)
: I2C_START_SEND);
}
+void i2c_bus_master(I2CBus *bus, QEMUBH *bh)
+{
+ if (i2c_bus_busy(bus)) {
+ I2CPendingMaster *node = g_new(struct I2CPendingMaster, 1);
+ node->bh = bh;
+
+ QSIMPLEQ_INSERT_TAIL(&bus->pending_masters, node, entry);
+
+ return;
+ }
+
+ bus->bh = bh;
+ qemu_bh_schedule(bus->bh);
+}
+
+void i2c_bus_release(I2CBus *bus)
+{
+ bus->bh = NULL;
+}
+
int i2c_start_recv(I2CBus *bus, uint8_t address)
{
return i2c_do_start_transfer(bus, address, I2C_START_RECV);
@@ -206,6 +228,16 @@ void i2c_end_transfer(I2CBus *bus)
g_free(node);
}
bus->broadcast = false;
+
+ if (!QSIMPLEQ_EMPTY(&bus->pending_masters)) {
+ I2CPendingMaster *node = QSIMPLEQ_FIRST(&bus->pending_masters);
+ bus->bh = node->bh;
+
+ QSIMPLEQ_REMOVE_HEAD(&bus->pending_masters, entry);
+ g_free(node);
+
+ qemu_bh_schedule(bus->bh);
+ }
}
int i2c_send(I2CBus *bus, uint8_t data)
diff --git a/include/hw/i2c/i2c.h b/include/hw/i2c/i2c.h
index 5ca3b708c0be..be8bb8b78a60 100644
--- a/include/hw/i2c/i2c.h
+++ b/include/hw/i2c/i2c.h
@@ -69,13 +69,25 @@ struct I2CNode {
QLIST_ENTRY(I2CNode) next;
};
+typedef struct I2CPendingMaster I2CPendingMaster;
+
+struct I2CPendingMaster {
+ QEMUBH *bh;
+ QSIMPLEQ_ENTRY(I2CPendingMaster) entry;
+};
+
typedef QLIST_HEAD(I2CNodeList, I2CNode) I2CNodeList;
+typedef QSIMPLEQ_HEAD(I2CPendingMasters, I2CPendingMaster) I2CPendingMasters;
struct I2CBus {
BusState qbus;
I2CNodeList current_devs;
+ I2CPendingMasters pending_masters;
uint8_t saved_address;
bool broadcast;
+
+ /* Set from slave currently mastering the bus. */
+ QEMUBH *bh;
};
I2CBus *i2c_init_bus(DeviceState *parent, const char *name);
@@ -117,6 +129,8 @@ int i2c_start_send(I2CBus *bus, uint8_t address);
void i2c_end_transfer(I2CBus *bus);
void i2c_nack(I2CBus *bus);
+void i2c_bus_master(I2CBus *bus, QEMUBH *bh);
+void i2c_bus_release(I2CBus *bus);
int i2c_send(I2CBus *bus, uint8_t data);
uint8_t i2c_recv(I2CBus *bus);
bool i2c_scan_bus(I2CBus *bus, uint8_t address, bool broadcast,
--
2.35.1
next prev parent reply other threads:[~2022-03-31 17:04 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-31 16:57 [RFC PATCH 0/4] hw/i2c: i2c slave mode support Klaus Jensen
2022-03-31 16:57 ` Klaus Jensen [this message]
2022-03-31 16:57 ` [RFC PATCH 2/4] hw/i2c: add async send Klaus Jensen
2022-03-31 16:57 ` [RFC PATCH 3/4] hw/i2c: add slave mode for aspeed_i2c Klaus Jensen
2022-03-31 20:44 ` Philippe Mathieu-Daudé
2022-04-01 6:30 ` Klaus Jensen
2022-04-06 6:14 ` Cédric Le Goater
2022-04-06 7:40 ` Klaus Jensen
2022-04-06 8:52 ` Cédric Le Goater
2022-04-06 9:16 ` Klaus Jensen
2022-04-06 9:44 ` Cédric Le Goater
2022-03-31 16:57 ` [RFC PATCH 4/4] hw/misc: add a toy i2c echo device Klaus Jensen
2022-03-31 20:32 ` [RFC PATCH 0/4] hw/i2c: i2c slave mode support Corey Minyard
2022-04-01 6:29 ` Klaus Jensen
2022-04-01 8:58 ` Damien Hedde
2022-04-01 9:05 ` Klaus Jensen
2022-04-01 13:06 ` Corey Minyard
2022-04-05 20:52 ` Peter Delevoryas
2022-04-06 6:07 ` Klaus Jensen
2022-04-06 17:03 ` Peter Delevoryas
2022-04-06 18:41 ` Klaus Jensen
2022-04-06 22:06 ` Peter Delevoryas
2022-05-06 14:07 ` Jonathan Cameron via
2022-05-06 16:49 ` Cédric Le Goater
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