// SPDX-License-Identifier: GPL-2.0 /* * Renesas RIIC driver * * Copyright (C) 2013 Wolfram Sang <[email protected]> * Copyright (C) 2013 Renesas Solutions Corp. */ /* * This i2c core has a lot of interrupts, namely 8. We use their chaining as * some kind of state machine. * * 1) The main xfer routine kicks off a transmission by putting the start bit * (or repeated start) on the bus and enabling the transmit interrupt (TIE) * since we need to send the target address + RW bit in every case. * * 2) TIE sends target address + RW bit and selects how to continue. * * 3a) Write case: We keep utilizing TIE as long as we have data to send. If we * are done, we switch over to the transmission done interrupt (TEIE) and mark * the message as completed (includes sending STOP) there. * * 3b) Read case: We switch over to receive interrupt (RIE). One dummy read is * needed to start clocking, then we keep receiving until we are done. Note * that we use the RDRFS mode all the time, i.e. we ACK/NACK every byte by * writing to the ACKBT bit. I tried using the RDRFS mode only at the end of a * message to create the final NACK as sketched in the datasheet. This caused * some subtle races (when byte n was processed and byte n+1 was already * waiting), though, and I started with the safe approach. * * 4) If we got a NACK somewhere, we flag the error and stop the transmission * via NAKIE. * * Also check the comments in the interrupt routines for some gory details. */ #include <linux/clk.h> #include <linux/completion.h> #include <linux/err.h> #include <linux/i2c.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/pm_runtime.h> #include <linux/reset.h> #define ICCR1_ICE … #define ICCR1_IICRST … #define ICCR1_SOWP … #define ICCR2_BBSY … #define ICCR2_SP … #define ICCR2_RS … #define ICCR2_ST … #define ICMR1_CKS_MASK … #define ICMR1_BCWP … #define ICMR1_CKS(_x) … #define ICMR3_RDRFS … #define ICMR3_ACKWP … #define ICMR3_ACKBT … #define ICIER_TIE … #define ICIER_TEIE … #define ICIER_RIE … #define ICIER_NAKIE … #define ICIER_SPIE … #define ICSR2_NACKF … #define ICBR_RESERVED … #define RIIC_INIT_MSG … enum riic_reg_list { … }; struct riic_of_data { … }; struct riic_dev { … }; struct riic_irq_desc { … }; static inline void riic_writeb(struct riic_dev *riic, u8 val, u8 offset) { … } static inline u8 riic_readb(struct riic_dev *riic, u8 offset) { … } static inline void riic_clear_set_bit(struct riic_dev *riic, u8 clear, u8 set, u8 reg) { … } static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) { … } static irqreturn_t riic_tdre_isr(int irq, void *data) { … } static irqreturn_t riic_tend_isr(int irq, void *data) { … } static irqreturn_t riic_rdrf_isr(int irq, void *data) { … } static irqreturn_t riic_stop_isr(int irq, void *data) { … } static u32 riic_func(struct i2c_adapter *adap) { … } static const struct i2c_algorithm riic_algo = …; static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t) { … } static struct riic_irq_desc riic_irqs[] = …; static void riic_reset_control_assert(void *data) { … } static int riic_i2c_probe(struct platform_device *pdev) { … } static void riic_i2c_remove(struct platform_device *pdev) { … } static const struct riic_of_data riic_rz_a_info = …; static const struct riic_of_data riic_rz_v2h_info = …; static const struct of_device_id riic_i2c_dt_ids[] = …; static struct platform_driver riic_i2c_driver = …; module_platform_driver(…) …; MODULE_DESCRIPTION(…) …; MODULE_AUTHOR(…) …; MODULE_LICENSE(…) …; MODULE_DEVICE_TABLE(of, riic_i2c_dt_ids);
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