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[124.158.97.178]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2babaad7b68sm24663835ad.22.2026.05.07.05.05.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 May 2026 05:05:44 -0700 (PDT) From: Nicholas Piggin To: Corey Minyard Cc: Nicholas Piggin , Alistair Francis , Daniel Henrique Barboza , Chao Liu , Chris Rauer , Michael Ellerman , Joel Stanley , Anirudh Srinivasan , Portia Stephens , qemu-riscv@nongnu.org, qemu-devel@nongnu.org, Hao Wu , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Subject: [PATCH 2/4] [RFC] hw/i2c/designware_i2c: Switch to Fifo8 Date: Thu, 7 May 2026 22:05:20 +1000 Message-ID: <20260507120524.111056-3-npiggin@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260507120524.111056-1-npiggin@gmail.com> References: <20260507120524.111056-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::62f; envelope-from=npiggin@gmail.com; helo=mail-pl1-x62f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Alistair suggested moving to Fifo8, which I think is a good improvement. Broken out for individual review, but IMO we should squash before merge since it changes VMState format. Signed-off-by: Nicholas Piggin --- hw/i2c/designware_i2c.c | 37 ++++++++++++++++++++------------- include/hw/i2c/designware_i2c.h | 7 +++---- 2 files changed, 25 insertions(+), 19 deletions(-) diff --git a/hw/i2c/designware_i2c.c b/hw/i2c/designware_i2c.c index 1e5505f571..83d0968580 100644 --- a/hw/i2c/designware_i2c.c +++ b/hw/i2c/designware_i2c.c @@ -208,10 +208,8 @@ static void dw_i2c_update_irq(DesignWareI2CState *s) qemu_set_irq(s->irq, level); } -static uint32_t dw_i2c_read_ic_data_cmd(DesignWareI2CState *s) +static uint8_t dw_i2c_read_ic_data_cmd(DesignWareI2CState *s) { - uint32_t value = s->rx_fifo[s->rx_cur]; - if (s->status != DW_I2C_STATUS_RECEIVING) { qemu_log_mask(LOG_GUEST_ERROR, "%s: Attempted to read from RX fifo when not in receive " @@ -223,22 +221,21 @@ static uint32_t dw_i2c_read_ic_data_cmd(DesignWareI2CState *s) return 0; } - s->rx_cur = (s->rx_cur + 1) % DESIGNWARE_I2C_RX_FIFO_SIZE; + g_assert(s->ic_rxflr == fifo8_num_used(&s->rx_fifo)); - if (s->ic_rxflr > 0) { - s->ic_rxflr--; - } else { + if (fifo8_is_empty(&s->rx_fifo)) { s->ic_raw_intr_stat |= DW_IC_INTR_RX_UNDER; dw_i2c_update_irq(s); return 0; } + s->ic_rxflr--; if (s->ic_rxflr <= s->ic_rx_tl) { s->ic_raw_intr_stat &= ~DW_IC_INTR_RX_FULL; dw_i2c_update_irq(s); } - return value; + return fifo8_pop(&s->rx_fifo); } static uint64_t dw_i2c_read(void *opaque, hwaddr offset, unsigned size) @@ -445,6 +442,7 @@ static void dw_i2c_reset_to_idle(DesignWareI2CState *s) s->ic_raw_intr_stat &= ~DW_IC_INTR_RX_UNDER; s->ic_raw_intr_stat &= ~DW_IC_INTR_RX_OVER; s->ic_rxflr = 0; + fifo8_reset(&s->rx_fifo); s->ic_status &= ~DW_IC_STATUS_ACTIVITY; s->status = DW_I2C_STATUS_IDLE; dw_i2c_update_irq(s); @@ -509,10 +507,10 @@ static void dw_i2c_write_ic_data_cmd(DesignWareI2CState *s, uint32_t value) /* Receive data */ if (recv) { - uint8_t pos = (s->rx_cur + s->ic_rxflr) % DESIGNWARE_I2C_RX_FIFO_SIZE; + g_assert(s->ic_rxflr == fifo8_num_used(&s->rx_fifo)); - if (s->ic_rxflr < DESIGNWARE_I2C_RX_FIFO_SIZE) { - s->rx_fifo[pos] = i2c_recv(s->bus); + if (!fifo8_is_full(&s->rx_fifo)) { + fifo8_push(&s->rx_fifo, i2c_recv(s->bus)); s->ic_rxflr++; } else { s->ic_raw_intr_stat |= DW_IC_INTR_RX_OVER; @@ -738,7 +736,8 @@ static void designware_i2c_enter_reset(Object *obj, ResetType type) s->ic_comp_version = DW_IC_COMP_VERSION_INIT_VAL; s->ic_comp_type = DW_IC_COMP_TYPE_INIT_VAL; - s->rx_cur = 0; + fifo8_reset(&s->rx_fifo); + s->status = DW_I2C_STATUS_IDLE; } @@ -777,10 +776,8 @@ static const VMStateDescription vmstate_designware_i2c = { VMSTATE_UINT32(ic_comp_param_1, DesignWareI2CState), VMSTATE_UINT32(ic_comp_version, DesignWareI2CState), VMSTATE_UINT32(ic_comp_type, DesignWareI2CState), + VMSTATE_FIFO8(rx_fifo, DesignWareI2CState), VMSTATE_UINT32(status, DesignWareI2CState), - VMSTATE_UINT8_ARRAY(rx_fifo, DesignWareI2CState, - DESIGNWARE_I2C_RX_FIFO_SIZE), - VMSTATE_UINT8(rx_cur, DesignWareI2CState), VMSTATE_END_OF_LIST(), }, }; @@ -790,6 +787,8 @@ static void designware_i2c_smbus_init(Object *obj) DesignWareI2CState *s = DESIGNWARE_I2C(obj); SysBusDevice *sbd = SYS_BUS_DEVICE(obj); + fifo8_create(&s->rx_fifo, DESIGNWARE_I2C_RX_FIFO_SIZE); + sysbus_init_irq(sbd, &s->irq); memory_region_init_io(&s->iomem, obj, &designware_i2c_ops, s, @@ -799,6 +798,13 @@ static void designware_i2c_smbus_init(Object *obj) s->bus = i2c_init_bus(DEVICE(s), "i2c-bus"); } +static void designware_i2c_finalize(Object *obj) +{ + DesignWareI2CState *s = DESIGNWARE_I2C(obj); + + fifo8_destroy(&s->rx_fifo); +} + static void designware_i2c_class_init(ObjectClass *klass, const void *data) { ResettableClass *rc = RESETTABLE_CLASS(klass); @@ -819,6 +825,7 @@ static const TypeInfo designware_i2c_types[] = { .instance_size = sizeof(DesignWareI2CState), .class_init = designware_i2c_class_init, .instance_init = designware_i2c_smbus_init, + .instance_finalize = designware_i2c_finalize, }, }; DEFINE_TYPES(designware_i2c_types); diff --git a/include/hw/i2c/designware_i2c.h b/include/hw/i2c/designware_i2c.h index 71d74c9141..affaf983a2 100644 --- a/include/hw/i2c/designware_i2c.h +++ b/include/hw/i2c/designware_i2c.h @@ -8,6 +8,7 @@ #ifndef DESIGNWARE_I2C_H #define DESIGNWARE_I2C_H +#include "qemu/fifo8.h" #include "hw/i2c/i2c.h" #include "hw/core/irq.h" #include "hw/core/sysbus.h" @@ -53,8 +54,6 @@ typedef enum DesignWareI2CStatus { * @ic_comp_version: I2C component version register * @ic_comp_type: I2C component type register * @rx_fifo: The FIFO buffer for receiving in FIFO mode. - * @rx_cur: The current position of rx_fifo. - * @status: The current status of the SMBus. */ typedef struct DesignWareI2CState { SysBusDevice parent_obj; @@ -88,8 +87,8 @@ typedef struct DesignWareI2CState { uint32_t ic_comp_version; uint32_t ic_comp_type; - uint8_t rx_fifo[DESIGNWARE_I2C_RX_FIFO_SIZE]; - uint8_t rx_cur; + /* fifo8_num_used(rx_fifo) should always equal ic_rxflr */ + Fifo8 rx_fifo; DesignWareI2CStatus status; } DesignWareI2CState; -- 2.53.0