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378 lines
7.9 KiB
378 lines
7.9 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* I2C bus driver for Conexant Digicolor SoCs |
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* |
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* Author: Baruch Siach <[email protected]> |
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* |
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* Copyright (C) 2015 Paradox Innovation Ltd. |
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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/delay.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/kernel.h> |
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#include <linux/module.h> |
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#include <linux/of.h> |
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#include <linux/platform_device.h> |
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#define TIMEOUT_MS 100 |
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#define II_CONTROL 0x0 |
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#define II_CONTROL_LOCAL_RESET BIT(0) |
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#define II_CLOCKTIME 0x1 |
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#define II_COMMAND 0x2 |
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#define II_CMD_START 1 |
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#define II_CMD_RESTART 2 |
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#define II_CMD_SEND_ACK 3 |
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#define II_CMD_GET_ACK 6 |
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#define II_CMD_GET_NOACK 7 |
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#define II_CMD_STOP 10 |
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#define II_COMMAND_GO BIT(7) |
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#define II_COMMAND_COMPLETION_STATUS(r) (((r) >> 5) & 3) |
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#define II_CMD_STATUS_NORMAL 0 |
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#define II_CMD_STATUS_ACK_GOOD 1 |
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#define II_CMD_STATUS_ACK_BAD 2 |
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#define II_CMD_STATUS_ABORT 3 |
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#define II_DATA 0x3 |
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#define II_INTFLAG_CLEAR 0x8 |
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#define II_INTENABLE 0xa |
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struct dc_i2c { |
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struct i2c_adapter adap; |
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struct device *dev; |
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void __iomem *regs; |
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struct clk *clk; |
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unsigned int frequency; |
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struct i2c_msg *msg; |
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unsigned int msgbuf_ptr; |
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int last; |
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spinlock_t lock; |
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struct completion done; |
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int state; |
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int error; |
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}; |
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enum { |
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STATE_IDLE, |
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STATE_START, |
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STATE_ADDR, |
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STATE_WRITE, |
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STATE_READ, |
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STATE_STOP, |
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}; |
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static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd) |
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{ |
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writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND); |
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} |
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static u8 dc_i2c_addr_cmd(struct i2c_msg *msg) |
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{ |
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u8 addr = (msg->addr & 0x7f) << 1; |
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if (msg->flags & I2C_M_RD) |
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addr |= 1; |
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return addr; |
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} |
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static void dc_i2c_data(struct dc_i2c *i2c, u8 data) |
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{ |
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writeb_relaxed(data, i2c->regs + II_DATA); |
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} |
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static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte) |
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{ |
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dc_i2c_data(i2c, byte); |
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dc_i2c_cmd(i2c, II_CMD_SEND_ACK); |
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} |
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static void dc_i2c_write_buf(struct dc_i2c *i2c) |
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{ |
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dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]); |
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} |
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static void dc_i2c_next_read(struct dc_i2c *i2c) |
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{ |
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bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len); |
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dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK); |
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} |
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static void dc_i2c_stop(struct dc_i2c *i2c) |
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{ |
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i2c->state = STATE_STOP; |
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if (i2c->last) |
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dc_i2c_cmd(i2c, II_CMD_STOP); |
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else |
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complete(&i2c->done); |
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} |
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static u8 dc_i2c_read_byte(struct dc_i2c *i2c) |
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{ |
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return readb_relaxed(i2c->regs + II_DATA); |
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} |
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static void dc_i2c_read_buf(struct dc_i2c *i2c) |
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{ |
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i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c); |
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dc_i2c_next_read(i2c); |
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} |
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static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable) |
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{ |
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if (enable) |
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writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR); |
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writeb_relaxed(!!enable, i2c->regs + II_INTENABLE); |
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} |
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static int dc_i2c_cmd_status(struct dc_i2c *i2c) |
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{ |
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u8 cmd = readb_relaxed(i2c->regs + II_COMMAND); |
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return II_COMMAND_COMPLETION_STATUS(cmd); |
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} |
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static void dc_i2c_start_msg(struct dc_i2c *i2c, int first) |
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{ |
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struct i2c_msg *msg = i2c->msg; |
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if (!(msg->flags & I2C_M_NOSTART)) { |
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i2c->state = STATE_START; |
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dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART); |
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} else if (msg->flags & I2C_M_RD) { |
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i2c->state = STATE_READ; |
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dc_i2c_next_read(i2c); |
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} else { |
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i2c->state = STATE_WRITE; |
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dc_i2c_write_buf(i2c); |
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} |
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} |
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static irqreturn_t dc_i2c_irq(int irq, void *dev_id) |
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{ |
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struct dc_i2c *i2c = dev_id; |
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int cmd_status = dc_i2c_cmd_status(i2c); |
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u8 addr_cmd; |
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writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR); |
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spin_lock(&i2c->lock); |
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if (cmd_status == II_CMD_STATUS_ACK_BAD |
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|| cmd_status == II_CMD_STATUS_ABORT) { |
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i2c->error = -EIO; |
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complete(&i2c->done); |
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goto out; |
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} |
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switch (i2c->state) { |
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case STATE_START: |
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addr_cmd = dc_i2c_addr_cmd(i2c->msg); |
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dc_i2c_write_byte(i2c, addr_cmd); |
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i2c->state = STATE_ADDR; |
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break; |
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case STATE_ADDR: |
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if (i2c->msg->flags & I2C_M_RD) { |
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dc_i2c_next_read(i2c); |
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i2c->state = STATE_READ; |
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break; |
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} |
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i2c->state = STATE_WRITE; |
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fallthrough; |
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case STATE_WRITE: |
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if (i2c->msgbuf_ptr < i2c->msg->len) |
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dc_i2c_write_buf(i2c); |
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else |
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dc_i2c_stop(i2c); |
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break; |
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case STATE_READ: |
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if (i2c->msgbuf_ptr < i2c->msg->len) |
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dc_i2c_read_buf(i2c); |
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else |
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dc_i2c_stop(i2c); |
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break; |
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case STATE_STOP: |
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i2c->state = STATE_IDLE; |
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complete(&i2c->done); |
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break; |
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} |
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out: |
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spin_unlock(&i2c->lock); |
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return IRQ_HANDLED; |
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} |
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static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first, |
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int last) |
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{ |
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unsigned long timeout = msecs_to_jiffies(TIMEOUT_MS); |
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unsigned long flags; |
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spin_lock_irqsave(&i2c->lock, flags); |
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i2c->msg = msg; |
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i2c->msgbuf_ptr = 0; |
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i2c->last = last; |
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i2c->error = 0; |
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reinit_completion(&i2c->done); |
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dc_i2c_set_irq(i2c, 1); |
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dc_i2c_start_msg(i2c, first); |
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spin_unlock_irqrestore(&i2c->lock, flags); |
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timeout = wait_for_completion_timeout(&i2c->done, timeout); |
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dc_i2c_set_irq(i2c, 0); |
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if (timeout == 0) { |
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i2c->state = STATE_IDLE; |
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return -ETIMEDOUT; |
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} |
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if (i2c->error) |
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return i2c->error; |
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return 0; |
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} |
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static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) |
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{ |
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struct dc_i2c *i2c = adap->algo_data; |
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int i, ret; |
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for (i = 0; i < num; i++) { |
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ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1); |
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if (ret) |
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return ret; |
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} |
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return num; |
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} |
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static int dc_i2c_init_hw(struct dc_i2c *i2c) |
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{ |
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unsigned long clk_rate = clk_get_rate(i2c->clk); |
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unsigned int clocktime; |
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writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL); |
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udelay(100); |
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writeb_relaxed(0, i2c->regs + II_CONTROL); |
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udelay(100); |
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clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency); |
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if (clocktime < 1 || clocktime > 0xff) { |
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dev_err(i2c->dev, "can't set bus speed of %u Hz\n", |
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i2c->frequency); |
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return -EINVAL; |
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} |
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writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME); |
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return 0; |
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} |
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static u32 dc_i2c_func(struct i2c_adapter *adap) |
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{ |
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART; |
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} |
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static const struct i2c_algorithm dc_i2c_algorithm = { |
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.master_xfer = dc_i2c_xfer, |
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.functionality = dc_i2c_func, |
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}; |
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static int dc_i2c_probe(struct platform_device *pdev) |
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{ |
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struct device_node *np = pdev->dev.of_node; |
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struct dc_i2c *i2c; |
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int ret = 0, irq; |
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i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL); |
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if (!i2c) |
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return -ENOMEM; |
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if (of_property_read_u32(pdev->dev.of_node, "clock-frequency", |
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&i2c->frequency)) |
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i2c->frequency = I2C_MAX_STANDARD_MODE_FREQ; |
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i2c->dev = &pdev->dev; |
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platform_set_drvdata(pdev, i2c); |
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spin_lock_init(&i2c->lock); |
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init_completion(&i2c->done); |
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i2c->clk = devm_clk_get(&pdev->dev, NULL); |
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if (IS_ERR(i2c->clk)) |
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return PTR_ERR(i2c->clk); |
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i2c->regs = devm_platform_ioremap_resource(pdev, 0); |
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if (IS_ERR(i2c->regs)) |
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return PTR_ERR(i2c->regs); |
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irq = platform_get_irq(pdev, 0); |
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if (irq < 0) |
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return irq; |
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ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0, |
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dev_name(&pdev->dev), i2c); |
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if (ret < 0) |
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return ret; |
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strlcpy(i2c->adap.name, "Conexant Digicolor I2C adapter", |
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sizeof(i2c->adap.name)); |
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i2c->adap.owner = THIS_MODULE; |
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i2c->adap.algo = &dc_i2c_algorithm; |
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i2c->adap.dev.parent = &pdev->dev; |
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i2c->adap.dev.of_node = np; |
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i2c->adap.algo_data = i2c; |
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ret = dc_i2c_init_hw(i2c); |
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if (ret) |
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return ret; |
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ret = clk_prepare_enable(i2c->clk); |
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if (ret < 0) |
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return ret; |
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ret = i2c_add_adapter(&i2c->adap); |
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if (ret < 0) { |
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clk_disable_unprepare(i2c->clk); |
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return ret; |
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} |
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return 0; |
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} |
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static int dc_i2c_remove(struct platform_device *pdev) |
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{ |
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struct dc_i2c *i2c = platform_get_drvdata(pdev); |
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i2c_del_adapter(&i2c->adap); |
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clk_disable_unprepare(i2c->clk); |
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return 0; |
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} |
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static const struct of_device_id dc_i2c_match[] = { |
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{ .compatible = "cnxt,cx92755-i2c" }, |
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{ }, |
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}; |
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MODULE_DEVICE_TABLE(of, dc_i2c_match); |
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static struct platform_driver dc_i2c_driver = { |
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.probe = dc_i2c_probe, |
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.remove = dc_i2c_remove, |
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.driver = { |
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.name = "digicolor-i2c", |
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.of_match_table = dc_i2c_match, |
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}, |
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}; |
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module_platform_driver(dc_i2c_driver); |
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MODULE_AUTHOR("Baruch Siach <[email protected]>"); |
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MODULE_DESCRIPTION("Conexant Digicolor I2C master driver"); |
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MODULE_LICENSE("GPL v2");
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