515 lines
13 KiB
C
515 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Renesas RIIC driver
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*
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* Copyright (C) 2013 Wolfram Sang <wsa@sang-engineering.com>
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* Copyright (C) 2013 Renesas Solutions Corp.
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*/
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/*
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* This i2c core has a lot of interrupts, namely 8. We use their chaining as
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* some kind of state machine.
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*
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* 1) The main xfer routine kicks off a transmission by putting the start bit
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* (or repeated start) on the bus and enabling the transmit interrupt (TIE)
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* since we need to send the slave address + RW bit in every case.
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*
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* 2) TIE sends slave address + RW bit and selects how to continue.
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*
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* 3a) Write case: We keep utilizing TIE as long as we have data to send. If we
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* are done, we switch over to the transmission done interrupt (TEIE) and mark
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* the message as completed (includes sending STOP) there.
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*
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* 3b) Read case: We switch over to receive interrupt (RIE). One dummy read is
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* needed to start clocking, then we keep receiving until we are done. Note
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* that we use the RDRFS mode all the time, i.e. we ACK/NACK every byte by
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* writing to the ACKBT bit. I tried using the RDRFS mode only at the end of a
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* message to create the final NACK as sketched in the datasheet. This caused
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* some subtle races (when byte n was processed and byte n+1 was already
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* waiting), though, and I started with the safe approach.
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*
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* 4) If we got a NACK somewhere, we flag the error and stop the transmission
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* via NAKIE.
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*
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* Also check the comments in the interrupt routines for some gory details.
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*/
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#include <linux/clk.h>
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#include <linux/completion.h>
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/platform_device.h>
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#include <linux/pm_runtime.h>
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#include <linux/reset.h>
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#define RIIC_ICCR1 0x00
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#define RIIC_ICCR2 0x04
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#define RIIC_ICMR1 0x08
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#define RIIC_ICMR3 0x10
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#define RIIC_ICSER 0x18
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#define RIIC_ICIER 0x1c
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#define RIIC_ICSR2 0x24
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#define RIIC_ICBRL 0x34
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#define RIIC_ICBRH 0x38
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#define RIIC_ICDRT 0x3c
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#define RIIC_ICDRR 0x40
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#define ICCR1_ICE 0x80
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#define ICCR1_IICRST 0x40
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#define ICCR1_SOWP 0x10
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#define ICCR2_BBSY 0x80
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#define ICCR2_SP 0x08
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#define ICCR2_RS 0x04
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#define ICCR2_ST 0x02
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#define ICMR1_CKS_MASK 0x70
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#define ICMR1_BCWP 0x08
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#define ICMR1_CKS(_x) ((((_x) << 4) & ICMR1_CKS_MASK) | ICMR1_BCWP)
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#define ICMR3_RDRFS 0x20
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#define ICMR3_ACKWP 0x10
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#define ICMR3_ACKBT 0x08
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#define ICIER_TIE 0x80
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#define ICIER_TEIE 0x40
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#define ICIER_RIE 0x20
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#define ICIER_NAKIE 0x10
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#define ICIER_SPIE 0x08
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#define ICSR2_NACKF 0x10
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#define ICBR_RESERVED 0xe0 /* Should be 1 on writes */
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#define RIIC_INIT_MSG -1
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enum riic_type {
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RIIC_RZ_A,
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RIIC_RZ_G2L,
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};
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struct riic_dev {
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void __iomem *base;
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u8 *buf;
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struct i2c_msg *msg;
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int bytes_left;
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int err;
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int is_last;
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struct completion msg_done;
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struct i2c_adapter adapter;
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struct clk *clk;
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};
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struct riic_irq_desc {
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int res_num;
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irq_handler_t isr;
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char *name;
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};
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static inline void riic_clear_set_bit(struct riic_dev *riic, u8 clear, u8 set, u8 reg)
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{
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writeb((readb(riic->base + reg) & ~clear) | set, riic->base + reg);
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}
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static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
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{
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struct riic_dev *riic = i2c_get_adapdata(adap);
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unsigned long time_left;
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int i;
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u8 start_bit;
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pm_runtime_get_sync(adap->dev.parent);
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if (readb(riic->base + RIIC_ICCR2) & ICCR2_BBSY) {
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riic->err = -EBUSY;
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goto out;
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}
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reinit_completion(&riic->msg_done);
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riic->err = 0;
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writeb(0, riic->base + RIIC_ICSR2);
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for (i = 0, start_bit = ICCR2_ST; i < num; i++) {
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riic->bytes_left = RIIC_INIT_MSG;
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riic->buf = msgs[i].buf;
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riic->msg = &msgs[i];
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riic->is_last = (i == num - 1);
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writeb(ICIER_NAKIE | ICIER_TIE, riic->base + RIIC_ICIER);
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writeb(start_bit, riic->base + RIIC_ICCR2);
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time_left = wait_for_completion_timeout(&riic->msg_done, riic->adapter.timeout);
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if (time_left == 0)
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riic->err = -ETIMEDOUT;
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if (riic->err)
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break;
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start_bit = ICCR2_RS;
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}
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out:
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pm_runtime_put(adap->dev.parent);
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return riic->err ?: num;
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}
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static irqreturn_t riic_tdre_isr(int irq, void *data)
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{
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struct riic_dev *riic = data;
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u8 val;
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if (!riic->bytes_left)
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return IRQ_NONE;
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if (riic->bytes_left == RIIC_INIT_MSG) {
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if (riic->msg->flags & I2C_M_RD)
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/* On read, switch over to receive interrupt */
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riic_clear_set_bit(riic, ICIER_TIE, ICIER_RIE, RIIC_ICIER);
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else
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/* On write, initialize length */
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riic->bytes_left = riic->msg->len;
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val = i2c_8bit_addr_from_msg(riic->msg);
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} else {
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val = *riic->buf;
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riic->buf++;
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riic->bytes_left--;
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}
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/*
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* Switch to transmission ended interrupt when done. Do check here
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* after bytes_left was initialized to support SMBUS_QUICK (new msg has
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* 0 length then)
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*/
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if (riic->bytes_left == 0)
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riic_clear_set_bit(riic, ICIER_TIE, ICIER_TEIE, RIIC_ICIER);
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/*
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* This acks the TIE interrupt. We get another TIE immediately if our
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* value could be moved to the shadow shift register right away. So
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* this must be after updates to ICIER (where we want to disable TIE)!
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*/
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writeb(val, riic->base + RIIC_ICDRT);
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return IRQ_HANDLED;
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}
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static irqreturn_t riic_tend_isr(int irq, void *data)
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{
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struct riic_dev *riic = data;
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if (readb(riic->base + RIIC_ICSR2) & ICSR2_NACKF) {
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/* We got a NACKIE */
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readb(riic->base + RIIC_ICDRR); /* dummy read */
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riic_clear_set_bit(riic, ICSR2_NACKF, 0, RIIC_ICSR2);
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riic->err = -ENXIO;
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} else if (riic->bytes_left) {
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return IRQ_NONE;
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}
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if (riic->is_last || riic->err) {
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riic_clear_set_bit(riic, ICIER_TEIE, ICIER_SPIE, RIIC_ICIER);
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writeb(ICCR2_SP, riic->base + RIIC_ICCR2);
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} else {
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/* Transfer is complete, but do not send STOP */
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riic_clear_set_bit(riic, ICIER_TEIE, 0, RIIC_ICIER);
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complete(&riic->msg_done);
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}
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return IRQ_HANDLED;
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}
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static irqreturn_t riic_rdrf_isr(int irq, void *data)
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{
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struct riic_dev *riic = data;
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if (!riic->bytes_left)
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return IRQ_NONE;
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if (riic->bytes_left == RIIC_INIT_MSG) {
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riic->bytes_left = riic->msg->len;
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readb(riic->base + RIIC_ICDRR); /* dummy read */
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return IRQ_HANDLED;
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}
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if (riic->bytes_left == 1) {
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/* STOP must come before we set ACKBT! */
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if (riic->is_last) {
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riic_clear_set_bit(riic, 0, ICIER_SPIE, RIIC_ICIER);
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writeb(ICCR2_SP, riic->base + RIIC_ICCR2);
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}
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riic_clear_set_bit(riic, 0, ICMR3_ACKBT, RIIC_ICMR3);
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} else {
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riic_clear_set_bit(riic, ICMR3_ACKBT, 0, RIIC_ICMR3);
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}
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/* Reading acks the RIE interrupt */
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*riic->buf = readb(riic->base + RIIC_ICDRR);
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riic->buf++;
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riic->bytes_left--;
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return IRQ_HANDLED;
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}
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static irqreturn_t riic_stop_isr(int irq, void *data)
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{
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struct riic_dev *riic = data;
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/* read back registers to confirm writes have fully propagated */
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writeb(0, riic->base + RIIC_ICSR2);
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readb(riic->base + RIIC_ICSR2);
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writeb(0, riic->base + RIIC_ICIER);
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readb(riic->base + RIIC_ICIER);
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complete(&riic->msg_done);
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return IRQ_HANDLED;
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}
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static u32 riic_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm riic_algo = {
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.master_xfer = riic_xfer,
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.functionality = riic_func,
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};
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static int riic_init_hw(struct riic_dev *riic, struct i2c_timings *t)
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{
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int ret = 0;
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unsigned long rate;
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int total_ticks, cks, brl, brh;
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pm_runtime_get_sync(riic->adapter.dev.parent);
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if (t->bus_freq_hz > I2C_MAX_FAST_MODE_FREQ) {
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dev_err(&riic->adapter.dev,
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"unsupported bus speed (%dHz). %d max\n",
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t->bus_freq_hz, I2C_MAX_FAST_MODE_FREQ);
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ret = -EINVAL;
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goto out;
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}
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rate = clk_get_rate(riic->clk);
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/*
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* Assume the default register settings:
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* FER.SCLE = 1 (SCL sync circuit enabled, adds 2 or 3 cycles)
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* FER.NFE = 1 (noise circuit enabled)
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* MR3.NF = 0 (1 cycle of noise filtered out)
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*
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* Freq (CKS=000) = (I2CCLK + tr + tf)/ (BRH + 3 + 1) + (BRL + 3 + 1)
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* Freq (CKS!=000) = (I2CCLK + tr + tf)/ (BRH + 2 + 1) + (BRL + 2 + 1)
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*/
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/*
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* Determine reference clock rate. We must be able to get the desired
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* frequency with only 62 clock ticks max (31 high, 31 low).
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* Aim for a duty of 60% LOW, 40% HIGH.
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*/
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total_ticks = DIV_ROUND_UP(rate, t->bus_freq_hz);
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for (cks = 0; cks < 7; cks++) {
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/*
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* 60% low time must be less than BRL + 2 + 1
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* BRL max register value is 0x1F.
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*/
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brl = ((total_ticks * 6) / 10);
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if (brl <= (0x1F + 3))
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break;
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total_ticks /= 2;
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rate /= 2;
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}
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if (brl > (0x1F + 3)) {
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dev_err(&riic->adapter.dev, "invalid speed (%lu). Too slow.\n",
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(unsigned long)t->bus_freq_hz);
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ret = -EINVAL;
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goto out;
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}
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brh = total_ticks - brl;
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/* Remove automatic clock ticks for sync circuit and NF */
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if (cks == 0) {
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brl -= 4;
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brh -= 4;
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} else {
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brl -= 3;
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brh -= 3;
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}
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/*
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* Remove clock ticks for rise and fall times. Convert ns to clock
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* ticks.
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*/
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brl -= t->scl_fall_ns / (1000000000 / rate);
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brh -= t->scl_rise_ns / (1000000000 / rate);
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/* Adjust for min register values for when SCLE=1 and NFE=1 */
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if (brl < 1)
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brl = 1;
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if (brh < 1)
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brh = 1;
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pr_debug("i2c-riic: freq=%lu, duty=%d, fall=%lu, rise=%lu, cks=%d, brl=%d, brh=%d\n",
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rate / total_ticks, ((brl + 3) * 100) / (brl + brh + 6),
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t->scl_fall_ns / (1000000000 / rate),
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t->scl_rise_ns / (1000000000 / rate), cks, brl, brh);
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/* Changing the order of accessing IICRST and ICE may break things! */
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writeb(ICCR1_IICRST | ICCR1_SOWP, riic->base + RIIC_ICCR1);
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riic_clear_set_bit(riic, 0, ICCR1_ICE, RIIC_ICCR1);
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writeb(ICMR1_CKS(cks), riic->base + RIIC_ICMR1);
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writeb(brh | ICBR_RESERVED, riic->base + RIIC_ICBRH);
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writeb(brl | ICBR_RESERVED, riic->base + RIIC_ICBRL);
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writeb(0, riic->base + RIIC_ICSER);
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writeb(ICMR3_ACKWP | ICMR3_RDRFS, riic->base + RIIC_ICMR3);
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riic_clear_set_bit(riic, ICCR1_IICRST, 0, RIIC_ICCR1);
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out:
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pm_runtime_put(riic->adapter.dev.parent);
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return ret;
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}
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static struct riic_irq_desc riic_irqs[] = {
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{ .res_num = 0, .isr = riic_tend_isr, .name = "riic-tend" },
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{ .res_num = 1, .isr = riic_rdrf_isr, .name = "riic-rdrf" },
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{ .res_num = 2, .isr = riic_tdre_isr, .name = "riic-tdre" },
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{ .res_num = 3, .isr = riic_stop_isr, .name = "riic-stop" },
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{ .res_num = 5, .isr = riic_tend_isr, .name = "riic-nack" },
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};
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static int riic_i2c_probe(struct platform_device *pdev)
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{
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struct riic_dev *riic;
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struct i2c_adapter *adap;
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struct resource *res;
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struct i2c_timings i2c_t;
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struct reset_control *rstc;
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int i, ret;
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enum riic_type type;
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riic = devm_kzalloc(&pdev->dev, sizeof(*riic), GFP_KERNEL);
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if (!riic)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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riic->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(riic->base))
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return PTR_ERR(riic->base);
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riic->clk = devm_clk_get(&pdev->dev, NULL);
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if (IS_ERR(riic->clk)) {
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dev_err(&pdev->dev, "missing controller clock");
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return PTR_ERR(riic->clk);
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}
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type = (enum riic_type)of_device_get_match_data(&pdev->dev);
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if (type == RIIC_RZ_G2L) {
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rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
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if (IS_ERR(rstc)) {
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dev_err(&pdev->dev, "Error: missing reset ctrl\n");
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return PTR_ERR(rstc);
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}
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reset_control_deassert(rstc);
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}
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for (i = 0; i < ARRAY_SIZE(riic_irqs); i++) {
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ret = platform_get_irq(pdev, riic_irqs[i].res_num);
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if (ret < 0)
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return ret;
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ret = devm_request_irq(&pdev->dev, ret, riic_irqs[i].isr,
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0, riic_irqs[i].name, riic);
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if (ret) {
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dev_err(&pdev->dev, "failed to request irq %s\n", riic_irqs[i].name);
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return ret;
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}
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}
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adap = &riic->adapter;
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i2c_set_adapdata(adap, riic);
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strlcpy(adap->name, "Renesas RIIC adapter", sizeof(adap->name));
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adap->owner = THIS_MODULE;
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adap->algo = &riic_algo;
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adap->dev.parent = &pdev->dev;
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adap->dev.of_node = pdev->dev.of_node;
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init_completion(&riic->msg_done);
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i2c_parse_fw_timings(&pdev->dev, &i2c_t, true);
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pm_runtime_enable(&pdev->dev);
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ret = riic_init_hw(riic, &i2c_t);
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if (ret)
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goto out;
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ret = i2c_add_adapter(adap);
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if (ret)
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goto out;
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platform_set_drvdata(pdev, riic);
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dev_info(&pdev->dev, "registered with %dHz bus speed\n",
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i2c_t.bus_freq_hz);
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return 0;
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out:
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pm_runtime_disable(&pdev->dev);
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return ret;
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}
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static int riic_i2c_remove(struct platform_device *pdev)
|
|
{
|
|
struct riic_dev *riic = platform_get_drvdata(pdev);
|
|
|
|
pm_runtime_get_sync(&pdev->dev);
|
|
writeb(0, riic->base + RIIC_ICIER);
|
|
pm_runtime_put(&pdev->dev);
|
|
i2c_del_adapter(&riic->adapter);
|
|
pm_runtime_disable(&pdev->dev);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct of_device_id riic_i2c_dt_ids[] = {
|
|
{ .compatible = "renesas,riic-r9a07g044", .data = (void *)RIIC_RZ_G2L },
|
|
{ .compatible = "renesas,riic-rz", .data = (void *)RIIC_RZ_A },
|
|
{ /* Sentinel */ },
|
|
};
|
|
|
|
static struct platform_driver riic_i2c_driver = {
|
|
.probe = riic_i2c_probe,
|
|
.remove = riic_i2c_remove,
|
|
.driver = {
|
|
.name = "i2c-riic",
|
|
.of_match_table = riic_i2c_dt_ids,
|
|
},
|
|
};
|
|
|
|
module_platform_driver(riic_i2c_driver);
|
|
|
|
MODULE_DESCRIPTION("Renesas RIIC adapter");
|
|
MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>");
|
|
MODULE_LICENSE("GPL v2");
|
|
MODULE_DEVICE_TABLE(of, riic_i2c_dt_ids);
|