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: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Fabrizio 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: Andi Shyti <andi.shyti@kernel.org>

diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c
index d7dddd6c296a2645c6cdb4146a10b4796003f30f..23375f7fe3ad3726f61957dabf68ba57bf6a19d1 100644 (file)
--- a/drivers/i2c/busses/i2c-riic.c
+++ b/drivers/i2c/busses/i2c-riic.c
@@ -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);