From c7b0a7c10752fa9a30f719848f4350fa02fdb8e5 Mon Sep 17 00:00:00 2001 From: Sifan Naeem Date: Thu, 19 Nov 2015 09:35:16 +0000 Subject: [PATCH] i2c: img-scb: add handle for Master halt interrupt Master halt is issued after each byte of a transaction is processed in IP version 3.3. Master halt will stall the bus by holding the SCK line low until the halt bit in the scb_general_control is cleared. After the last byte of a transfer is processed we can use the Master Halt interrupt to facilitate a repeated start transfer without issuing a stop bit. Signed-off-by: Sifan Naeem Reviewed-by: James Hartley Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-img-scb.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c index f416010a0b49..991118f837be 100644 --- a/drivers/i2c/busses/i2c-img-scb.c +++ b/drivers/i2c/busses/i2c-img-scb.c @@ -151,6 +151,7 @@ #define INT_FIFO_EMPTYING BIT(12) #define INT_TRANSACTION_DONE BIT(15) #define INT_SLAVE_EVENT BIT(16) +#define INT_MASTER_HALTED BIT(17) #define INT_TIMING BIT(18) #define INT_STOP_DETECTED BIT(19) @@ -177,6 +178,7 @@ INT_FIFO_FULL | \ INT_FIFO_FILLING | \ INT_FIFO_EMPTY | \ + INT_MASTER_HALTED | \ INT_STOP_DETECTED) #define INT_ENABLE_MASK_WAITSTOP (INT_SLAVE_EVENT | \ @@ -875,18 +877,27 @@ static unsigned int img_i2c_auto(struct img_i2c *i2c, } if (i2c->msg.flags & I2C_M_RD) { - if (int_status & INT_FIFO_FULL_FILLING) { + if (int_status & (INT_FIFO_FULL_FILLING | INT_MASTER_HALTED)) { img_i2c_read_fifo(i2c); if (i2c->msg.len == 0) return ISR_WAITSTOP; } } else { - if (int_status & INT_FIFO_EMPTY) { - if (i2c->msg.len == 0) + if (int_status & (INT_FIFO_EMPTY | INT_MASTER_HALTED)) { + if ((int_status & INT_FIFO_EMPTY) && + i2c->msg.len == 0) return ISR_WAITSTOP; img_i2c_write_fifo(i2c); } } + if (int_status & INT_MASTER_HALTED) { + /* + * Release and then enable transaction halt, to + * allow only a single byte to proceed. + */ + img_i2c_transaction_halt(i2c, false); + img_i2c_transaction_halt(i2c, !i2c->last_msg); + } return 0; } -- 2.34.1