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Thu, 01 May 2025 13:40:11 -0700 (PDT) From: Prabhakar X-Google-Original-From: Prabhakar To: Chris Brandt , Andi Shyti , Wolfram Sang , Geert Uytterhoeven , Andy Shevchenko Cc: linux-renesas-soc@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, Prabhakar , Biju Das , Fabrizio Castro , Lad Prabhakar Subject: [PATCH v10] i2c: riic: Implement bus recovery Date: Thu, 1 May 2025 21:40:03 +0100 Message-ID: <20250501204003.141134-1-prabhakar.mahadev-lad.rj@bp.renesas.com> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Lad Prabhakar 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 Reviewed-by: Wolfram Sang Tested-by: Wolfram Sang Reviewed-by: Fabrizio Castro --- v9->v10: - Fixed the order of defining ICCR1_SDAO and ICCR1_SCLO - Added Reviewed-by and Tested-by tags v8>->v9: - Dropped Tested-by and Reviewed-by tags from patch 1/2 - Updated commit message v7->v8: - Included Acks from Andy and Fabrizio. v6->v7: - https://lore.kernel.org/all/20250203143511.629140-1-prabhakar.mahadev-lad.rj@bp.renesas.com/ v2->v6: - Included RB and TB from Claudiu. v1->v2: - Used single register read to check SDA/SCL lines --- drivers/i2c/busses/i2c-riic.c | 53 +++++++++++++++++++++++++++++++++-- 1 file changed, 51 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c index d7dddd6c296a..23375f7fe3ad 100644 --- 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);