Skip to content

ot_i2c: Use matched address for ACQ start condition byte, not target address #229

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 14, 2025
Merged

ot_i2c: Use matched address for ACQ start condition byte, not target address #229

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
28 changes: 24 additions & 4 deletions hw/opentitan/ot_i2c.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -355,6 +355,9 @@ struct OtI2CState {
/* Target mode first address mask */
uint8_t address_mask_0;

/* Address that was matched to us */
uint8_t matched_address;

uint32_t pclk; /* Current input clock */
const char *clock_src_name; /* IRQ name once connected */

Expand All @@ -372,6 +375,11 @@ struct OtI2CTarget {
I2CSlave i2c;
};

static uint8_t ot_i2c_address_abyte(uint8_t address, bool read)
{
return (address << 1u) | (read ? 1u : 0);
}

static void ot_i2c_update_irqs(OtI2CState *s)
{
uint32_t state_masked = s->regs[R_INTR_STATE] & s->regs[R_INTR_ENABLE];
Expand Down Expand Up @@ -1166,13 +1174,18 @@ static int ot_i2c_target_event(I2CSlave *target, enum i2c_event event)

switch (event) {
case I2C_START_SEND_ASYNC:
/* Set the first byte to the target address + RW bit as 0. */
ot_i2c_target_set_acqdata(s, target->address << 1u, SIGNAL_START);
/* Set the first byte to the matched target address + RW bit as 0. */
ot_i2c_target_set_acqdata(s,
ot_i2c_address_abyte(s->matched_address,
false),
SIGNAL_START);
i2c_ack(s->bus);
break;
case I2C_START_RECV:
/* Set the first byte to the target address + RW bit as 1. */
ot_i2c_target_set_acqdata(s, target->address << 1u | 1u, SIGNAL_START);
ot_i2c_target_set_acqdata(s,
ot_i2c_address_abyte(s->matched_address,
true),
SIGNAL_START);
if (ot_fifo32_num_used(&s->target_rx_fifo) > 1) {
/*
* Potentially an unhandled condition in the ACQ fifo. Datasheet
Expand Down Expand Up @@ -1251,6 +1264,12 @@ static bool ot_i2c_target_match_and_add(I2CSlave *candidate, uint8_t address,
/* Check address, subject to address masking. */
if (broadcast || (s->address_mask_0 &&
(address & s->address_mask_0) == candidate->address)) {
/*
* Store the address that successfully matched to
* use the correct address for start condition
*/
s->matched_address = address;

I2CNode *node = g_new0(struct I2CNode, 1u);
node->elt = candidate;
QLIST_INSERT_HEAD(current_devs, node, next);
Expand Down Expand Up @@ -1333,6 +1352,7 @@ static void ot_i2c_reset_enter(Object *obj, ResetType type)

s->check_timings = true;
s->address_mask_0 = 0x0u;
s->matched_address = 0x0u;
}

static void ot_i2c_realize(DeviceState *dev, Error **errp)
Expand Down
Loading