i2c.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <device/mmio.h>
#include <assert.h>
#include <console/console.h>
#include <delay.h>
#include <device/i2c_simple.h>
#include <soc/addressmap.h>
#include <soc/grf.h>
#include <soc/soc.h>
#include <soc/i2c.h>
#include <soc/clock.h>
#include <stddef.h>
#include <stdint.h>
 
#define RETRY_COUNT     3
/* 100000us = 100ms */
#define I2C_TIMEOUT_US  100000
#define I2C_BUS_MAX     6
#define I2C_NOACK       2
#define I2C_TIMEOUT     3
 
#define i2c_info(x...) do {if (0) printk(BIOS_DEBUG, x); } while (0)
 
struct rk_i2c_regs {
        u32 i2c_con;
        u32 i2c_clkdiv;
        u32 i2c_mrxaddr;
        u32 i2c_mrxraddr;
        u32 i2c_mtxcnt;
        u32 i2c_mrxcnt;
        u32 i2c_ien;
        u32 i2c_ipd;
        u32 i2c_fcnt;
        u32 reserved0[(0x100 - 0x24) / 4];
        u32 txdata[8];
        u32 reserved1[(0x200 - 0x120) / 4];
        u32 rxdata[8];
};
 
static const uintptr_t i2c_bus[] = IC_BASES;
 
/* Con register bits. */
#define I2C_ACT2NAK                     (1<<6)
#define I2C_NAK                         (1<<5)
#define I2C_STOP                                (1<<4)
#define I2C_START                       (1<<3)
#define I2C_MODE_TX                     (0<<1)
#define I2C_MODE_TRX            (1<<1)
#define I2C_MODE_RX                     (2<<1)
#define I2C_EN                          (1<<0)
 
#define I2C_8BIT        (1<<24)
#define I2C_16BIT       (3<<24)
#define I2C_24BIT       (7<<24)
 
/* Mtxcnt register bits. */
#define I2C_CNT(cnt)            ((cnt) & 0x3F)
 
#define I2C_NAKRCVI     (1<<6)
#define I2C_STOPI       (1<<5)
#define I2C_STARTI      (1<<4)
#define I2C_MBRFI       (1<<3)
#define I2C_MBTFI       (1<<2)
#define I2C_BRFI        (1<<1)
#define I2C_BTFI        (1<<0)
#define I2C_CLEANI      0x7F
 
static int i2c_send_start(struct rk_i2c_regs *reg_addr)
{
        int res = 0;
        int timeout = I2C_TIMEOUT_US;
 
        i2c_info("I2c Start::Send Start bit\n");
        write32(&reg_addr->i2c_ipd, I2C_CLEANI);
        write32(&reg_addr->i2c_con, I2C_EN | I2C_START);
        while (timeout--) {
                if (read32(&reg_addr->i2c_ipd) & I2C_STARTI)
                        break;
                udelay(1);
        }
 
        if (timeout <= 0) {
                printk(BIOS_ERR, "I2C Start::Send Start Bit Timeout\n");
                res = I2C_TIMEOUT;
        }
 
        return res;
}
 
static int i2c_send_stop(struct rk_i2c_regs *reg_addr)
{
        int res = 0;
        int timeout = I2C_TIMEOUT_US;
 
        i2c_info("I2c Stop::Send Stop bit\n");
        write32(&reg_addr->i2c_ipd, I2C_CLEANI);
        write32(&reg_addr->i2c_con, I2C_EN | I2C_STOP);
        while (timeout--) {
                if (read32(&reg_addr->i2c_ipd) & I2C_STOPI)
                        break;
                udelay(1);
        }
        write32(&reg_addr->i2c_con, 0);
        if (timeout <= 0) {
                printk(BIOS_ERR, "I2C Stop::Send Stop Bit Timeout\n");
                res = I2C_TIMEOUT;
        }
 
        return res;
}
 
static int i2c_read(struct rk_i2c_regs *reg_addr, struct i2c_msg segment)
{
        int res = 0;
        uint8_t *data = segment.buf;
        unsigned int bytes_remaining = segment.len;
        unsigned int con = 0;
 
        write32(&reg_addr->i2c_mrxaddr, I2C_8BIT | segment.slave << 1 | 1);
        write32(&reg_addr->i2c_mrxraddr, 0);
        con = I2C_MODE_TRX | I2C_EN | I2C_ACT2NAK;
        while (bytes_remaining) {
                int timeout = CONFIG_I2C_TRANSFER_TIMEOUT_US;
                size_t size = MIN(bytes_remaining, 32);
                bytes_remaining -= size;
                if (!bytes_remaining)
                        con |= I2C_EN | I2C_NAK;
 
                i2c_info("I2C Read::%zu bytes\n", size);
                write32(&reg_addr->i2c_ipd, I2C_CLEANI);
                write32(&reg_addr->i2c_con, con);
                write32(&reg_addr->i2c_mrxcnt, size);
 
                while (timeout--) {
                        if (read32(&reg_addr->i2c_ipd) & I2C_NAKRCVI) {
                                write32(&reg_addr->i2c_mrxcnt, 0);
                                write32(&reg_addr->i2c_con, 0);
                                return I2C_NOACK;
                        }
                        if (read32(&reg_addr->i2c_ipd) & I2C_MBRFI)
                                break;
                        udelay(1);
                }
                if (timeout <= 0) {
                        printk(BIOS_ERR, "I2C Read::Recv Data Timeout\n");
                        write32(&reg_addr->i2c_mrxcnt, 0);
                        write32(&reg_addr->i2c_con, 0);
                        return I2C_TIMEOUT;
                }
 
                buffer_from_fifo32(data, size, &reg_addr->rxdata, 4, 4);
                data += size;
                con = I2C_MODE_RX | I2C_EN | I2C_ACT2NAK;
        }
        return res;
}
 
static int i2c_write(struct rk_i2c_regs *reg_addr, struct i2c_msg segment)
{
        int res = 0;
        uint8_t *data = segment.buf;
        int bytes_remaining = segment.len + 1;
 
        /* Prepend one byte for the slave address to the transfer. */
        u32 prefix = segment.slave << 1;
        int prefsz = 1;
 
        while (bytes_remaining) {
                int timeout = CONFIG_I2C_TRANSFER_TIMEOUT_US;
                size_t size = MIN(bytes_remaining, 32);
                buffer_to_fifo32_prefix(data, prefix, prefsz, size,
                                        &reg_addr->txdata, 4, 4);
                data += size - prefsz;
 
                i2c_info("I2C Write::%zu bytes\n", size);
                write32(&reg_addr->i2c_ipd, I2C_CLEANI);
                write32(&reg_addr->i2c_con,
                        I2C_EN | I2C_MODE_TX | I2C_ACT2NAK);
                write32(&reg_addr->i2c_mtxcnt, size);
 
                while (timeout--) {
                        if (read32(&reg_addr->i2c_ipd) & I2C_NAKRCVI) {
                                write32(&reg_addr->i2c_mtxcnt, 0);
                                write32(&reg_addr->i2c_con, 0);
                                return I2C_NOACK;
                        }
                        if (read32(&reg_addr->i2c_ipd) & I2C_MBTFI)
                                break;
                        udelay(1);
                }
 
                if (timeout <= 0) {
                        printk(BIOS_ERR, "I2C Write::Send Data Timeout\n");
                        write32(&reg_addr->i2c_mtxcnt, 0);
                        write32(&reg_addr->i2c_con, 0);
                        return I2C_TIMEOUT;
                }
 
                bytes_remaining -= size;
                prefsz = 0;
                prefix = 0;
        }
        return res;
}
 
static int i2c_do_xfer(void *reg_addr, struct i2c_msg segment)
{
        int res = 0;
 
        if (i2c_send_start(reg_addr))
                return I2C_TIMEOUT;
        if (segment.flags & I2C_M_RD)
                res = i2c_read(reg_addr, segment);
        else
                res = i2c_write(reg_addr, segment);
        return i2c_send_stop(reg_addr) || res;
}
 
int platform_i2c_transfer(unsigned int bus, struct i2c_msg *segments,
                          int seg_count)
{
        int i;
        int res = 0;
        struct rk_i2c_regs *regs = (struct rk_i2c_regs *)(i2c_bus[bus]);
        struct i2c_msg *seg = segments;
 
        for (i = 0; i < seg_count; i++, seg++) {
                res = i2c_do_xfer(regs, *seg);
                if (res)
                        break;
        }
        return res;
}
 
void i2c_init(unsigned int bus, unsigned int hz)
{
        unsigned int clk_div;
        unsigned int divl;
        unsigned int divh;
        unsigned int i2c_src_clk;
        unsigned int i2c_clk;
        struct rk_i2c_regs *regs = (struct rk_i2c_regs *)(i2c_bus[bus]);
 
        i2c_src_clk = rkclk_i2c_clock_for_bus(bus);
 
        /* SCL Divisor = 8*(CLKDIVL + 1 + CLKDIVH + 1)
           SCL = PCLK / SCLK Divisor */
        clk_div = DIV_ROUND_UP(i2c_src_clk, hz * 8);
        divh = clk_div * 3 / 7 - 1;
        divl = clk_div - divh - 2;
        i2c_clk = i2c_src_clk / (8 * (divl + 1 + divh + 1));
        printk(BIOS_DEBUG, "I2C bus %u: %uHz (divh = %u, divl = %u)\n",
               bus, i2c_clk, divh, divl);
        assert((divh < 65536) && (divl < 65536) && hz - i2c_clk < 15*KHz);
        write32(&regs->i2c_clkdiv, (divh << 16) | (divl << 0));
}