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Add a bus multiplexer device

Browse source 
This patch set adds a bus multiplexer and the necessary infrastructure
 in the I2C code to allow it to work.
 
 These are common on systems with lots of I2C devices, like an IPMI BMC.
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Merge remote-tracking branch 'remotes/cminyard/tags/for-qemu-6.1-v1' into staging

Add a bus multiplexer device

This patch set adds a bus multiplexer and the necessary infrastructure
in the I2C code to allow it to work.

These are common on systems with lots of I2C devices, like an IPMI BMC.

# gpg: Signature made Thu 13 May 2021 22:48:07 BST
# gpg:                using RSA key FD0D5CE67CE0F59A6688268661F38C90919BFF81
# gpg: Good signature from "Corey Minyard <cminyard@mvista.com>" [unknown]
# gpg:                 aka "Corey Minyard <minyard@acm.org>" [unknown]
# gpg:                 aka "Corey Minyard <corey@minyard.net>" [unknown]
# gpg:                 aka "Corey Minyard <minyard@mvista.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: FD0D 5CE6 7CE0 F59A 6688  2686 61F3 8C90 919B FF81

* remotes/cminyard/tags/for-qemu-6.1-v1:
  hw/i2c: add pca954x i2c-mux switch
  hw/i2c: move search to i2c_scan_bus method
  hw/i2c: add match method for device search
  hw/i2c: name I2CNode list in I2CBus

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell 2021-05-14 14:26:23 +01:00
commit 499063d00a
8 changed files with 383 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

17
include/hw/i2c/i2c.h
View file

@ -16,6 +16,7 @@ enum i2c_event {
I2C_NACK /* Masker NACKed a receive byte. */
};
typedef struct I2CNodeList I2CNodeList;
#define TYPE_I2C_SLAVE "i2c-slave"
OBJECT_DECLARE_TYPE(I2CSlave, I2CSlaveClass,
@ -39,6 +40,16 @@ struct I2CSlaveClass {
* return code is not used and should be zero.
*/
int (*event)(I2CSlave *s, enum i2c_event event);
/*
* Check if this device matches the address provided. Returns bool of
* true if it matches (or broadcast), and updates the device list, false
* otherwise.
*
* If broadcast is true, match should add the device and return true.
*/
bool (*match_and_add)(I2CSlave *candidate, uint8_t address, bool broadcast,
I2CNodeList *current_devs);
};
struct I2CSlave {
@ -58,9 +69,11 @@ struct I2CNode {
QLIST_ENTRY(I2CNode) next;
};
typedef QLIST_HEAD(I2CNodeList, I2CNode) I2CNodeList;
struct I2CBus {
BusState qbus;
QLIST_HEAD(, I2CNode) current_devs;
I2CNodeList current_devs;
uint8_t saved_address;
bool broadcast;
};
@ -74,6 +87,8 @@ void i2c_nack(I2CBus *bus);
int i2c_send_recv(I2CBus *bus, uint8_t *data, bool send);
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,
I2CNodeList *current_devs);
/**
* Create an I2C slave device on the heap.

19
include/hw/i2c/i2c_mux_pca954x.h Normal file
View file

@ -0,0 +1,19 @@
#ifndef QEMU_I2C_MUX_PCA954X
#define QEMU_I2C_MUX_PCA954X
#include "hw/i2c/i2c.h"
#define TYPE_PCA9546 "pca9546"
#define TYPE_PCA9548 "pca9548"
/**
* Retrieves the i2c bus associated with the specified channel on this i2c
* mux.
* @mux: an i2c mux device.
* @channel: the i2c channel requested
*
* Returns: a pointer to the associated i2c bus.
*/
I2CBus *pca954x_i2c_get_bus(I2CSlave *mux, uint8_t channel);
#endif