Commit ba9e1b52 authored by Lad Prabhakar's avatar Lad Prabhakar Committed by Andi Shyti
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i2c: riic: Implement bus recovery 



Implement I2C bus recovery support for the RIIC controller by making use
of software-controlled SCL and SDA line manipulation. The controller allows
forcing SCL and SDA levels through control bits, which enables generation
of manual clock pulses and a stop condition to free a stuck bus.

This implementation wires up the bus recovery mechanism using
i2c_generic_scl_recovery and provides get/set operations for SCL and SDA.

This allows the RIIC driver to recover from bus hang scenarios where SDA
is held low by a slave.

Signed-off-by: default avatarLad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: default avatarFabrizio Castro <fabrizio.castro.jz@renesas.com>
Link: https://lore.kernel.org/r/20250501204003.141134-1-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: default avatarAndi Shyti <andi.shyti@kernel.org>
parent 218d2318

drivers/i2c/busses/i2c-riic.c

+51 −2
Original line number Diff line number Diff line
@@ -52,6 +52,8 @@ 
#define ICCR1_ICE	BIT(7)

#define ICCR1_IICRST	BIT(6)

#define ICCR1_SOWP	BIT(4)

#define ICCR1_SCLO	BIT(3)

#define ICCR1_SDAO	BIT(2)

#define ICCR1_SCLI	BIT(1)

#define ICCR1_SDAI	BIT(0)
@@ -151,11 +153,11 @@ static int riic_bus_barrier(struct riic_dev *riic) 
	ret = readb_poll_timeout(riic->base + riic->info->regs[RIIC_ICCR2], val,

				 !(val & ICCR2_BBSY), 10, riic->adapter.timeout);

	if (ret)

		return ret;

		return i2c_recover_bus(&riic->adapter);



	if ((riic_readb(riic, RIIC_ICCR1) & (ICCR1_SDAI | ICCR1_SCLI)) !=

	     (ICCR1_SDAI | ICCR1_SCLI))

		return -EBUSY;

		return i2c_recover_bus(&riic->adapter);



	return 0;

}
@@ -439,6 +441,52 @@ static int riic_init_hw(struct riic_dev *riic) 
	return 0;

}



static int riic_get_scl(struct i2c_adapter *adap)

{

	struct riic_dev *riic = i2c_get_adapdata(adap);



	return !!(riic_readb(riic, RIIC_ICCR1) & ICCR1_SCLI);

}



static int riic_get_sda(struct i2c_adapter *adap)

{

	struct riic_dev *riic = i2c_get_adapdata(adap);



	return !!(riic_readb(riic, RIIC_ICCR1) & ICCR1_SDAI);

}



static void riic_set_scl(struct i2c_adapter *adap, int val)

{

	struct riic_dev *riic = i2c_get_adapdata(adap);



	if (val)

		riic_clear_set_bit(riic, ICCR1_SOWP, ICCR1_SCLO, RIIC_ICCR1);

	else

		riic_clear_set_bit(riic, ICCR1_SOWP | ICCR1_SCLO, 0, RIIC_ICCR1);



	riic_clear_set_bit(riic, 0, ICCR1_SOWP, RIIC_ICCR1);

}



static void riic_set_sda(struct i2c_adapter *adap, int val)

{

	struct riic_dev *riic = i2c_get_adapdata(adap);



	if (val)

		riic_clear_set_bit(riic, ICCR1_SOWP, ICCR1_SDAO, RIIC_ICCR1);

	else

		riic_clear_set_bit(riic, ICCR1_SOWP | ICCR1_SDAO, 0, RIIC_ICCR1);



	riic_clear_set_bit(riic, 0, ICCR1_SOWP, RIIC_ICCR1);

}



static struct i2c_bus_recovery_info riic_bri = {

	.recover_bus = i2c_generic_scl_recovery,

	.get_scl = riic_get_scl,

	.set_scl = riic_set_scl,

	.get_sda = riic_get_sda,

	.set_sda = riic_set_sda,

};



static const struct riic_irq_desc riic_irqs[] = {

	{ .res_num = 0, .isr = riic_tend_isr, .name = "riic-tend" },

	{ .res_num = 1, .isr = riic_rdrf_isr, .name = "riic-rdrf" },
@@ -495,6 +543,7 @@ static int riic_i2c_probe(struct platform_device *pdev) 
	adap->algo = &riic_algo;

	adap->dev.parent = dev;

	adap->dev.of_node = dev->of_node;

	adap->bus_recovery_info = &riic_bri;



	init_completion(&riic->msg_done);