On Sun, Jun 4, 2017 at 10:02 PM, Andrew Jeffery <and...@aj.id.au> wrote:
> On Fri, 2017-06-02 at 18:29 -0700, Brendan Higgins wrote:
>> Added initial master support for Aspeed I2C controller. Supports
>> fourteen busses present in AST24XX and AST25XX BMC SoCs by Aspeed.
>>
>> Signed-off-by: Brendan Higgins <brendanhigg...@google.com>
>
> I exercised this patch on an AST2500-based machine. The results were
> good, and the implementation copes fine with a workload that causes an
> oops in our (older, unrelated) out-of-tree bus driver.
>
> Tested-by: Andrew Jeffery <and...@aj.id.au>
Wolfram, could you take a look at these patches? Ben, Joel and others
seem to be happy with it and Marc said he would take the irqchip
stuff.
Cheers
>
>> ---
>> Changes for v2:
>> - Added single module_init (multiple was breaking some builds).
>> Changes for v3:
>> - Removed "bus" device tree param; now extracted from bus address
>> offset
>> Changes for v4:
>> - I2C adapter number is now generated dynamically unless specified
>> in alias.
>> Changes for v5:
>> - Removed irq_chip used to multiplex IRQ and replaced it with
>> dummy_irq_chip
>> along with some other IRQ cleanup.
>> - Addressed comments from Cedric, and Vladimir, mostly stylistic
>> things and
>> using devm managed resources.
>> - Increased max clock frequency before the bus is put in HighSpeed
>> mode, as
>> per Kachalov's comment.
>> Changes for v6:
>> - No longer arbitrarily restrict bus to be slave xor master.
>> - Pulled out "struct aspeed_i2c_controller" as a interrupt
>> controller.
>> - Pulled out slave support into its own commit.
>> - Rewrote code that sets clock divider register because the
>> original version
>> set it incorrectly.
>> - Rewrote the aspeed_i2c_master_irq handler because the old method
>> of
>> completing a completion in between restarts was too slow causing
>> devices to
>> misbehave.
>> - Added support for I2C_M_RECV_LEN which I had incorrectly said was
>> supported
>> before.
>> - Addressed other comments from Vladimir.
>> Changes for v7:
>> - Changed clock-frequency to bus-frequency
>> - Made some fixes to clock divider code
>> - Added hardware reset function
>> - Marked functions that need to be called with the lock held as
>> "unlocked"
>> - Did a bunch of clean up
>> Changes for v8:
>> - ACK IRQ status bits before doing anything else
>> - Added multi-master device tree property
>> - Do not send STOP commands after interrupt errors
>> - Fix SMBUS_QUICK emulation handling
>> - Removed highspeed clock code (I will do it in a later patch set)
>> - Use the platform_device name for the adapter name
>> - Reset for all failed recoveries
>> - Removed the "__" prefix from all of the non-thread safe functions
>> Changes for v9:
>> - No longer debug log after every address NACK
>> - Clear errors after reset
>> - No longer access clock while holding lock
>> - Ack all interrupts durring bus reset and initialization
>> Changes for v10:
>> - Added master_xfer_result field to struct aspeed_i2c_bus
>> ---
>> drivers/i2c/busses/Kconfig | 10 +
>> drivers/i2c/busses/Makefile | 1 +
>> drivers/i2c/busses/i2c-aspeed.c | 681
>> ++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 692 insertions(+)
>> create mode 100644 drivers/i2c/busses/i2c-aspeed.c
>>
>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>> index 144cbadc7c72..280f84a0d7d1 100644
>> --- a/drivers/i2c/busses/Kconfig
>> +++ b/drivers/i2c/busses/Kconfig
>> @@ -326,6 +326,16 @@ config I2C_POWERMAC
>>
>> comment "I2C system bus drivers (mostly embedded / system-on-chip)"
>>
>> +config I2C_ASPEED
>> + tristate "Aspeed I2C Controller"
>> + depends on ARCH_ASPEED
>> + help
>> + If you say yes to this option, support will be included
>> for the
>> + Aspeed I2C controller.
>> +
>> + This driver can also be built as a module. If so, the
>> module
>> + will be called i2c-aspeed.
>> +
>> config I2C_AT91
>> tristate "Atmel AT91 I2C Two-Wire interface (TWI)"
>> depends on ARCH_AT91
>> diff --git a/drivers/i2c/busses/Makefile
>> b/drivers/i2c/busses/Makefile
>> index 30b60855fbcd..e84604b9bf3b 100644
>> --- a/drivers/i2c/busses/Makefile
>> +++ b/drivers/i2c/busses/Makefile
>> @@ -29,6 +29,7 @@ obj-$(CONFIG_I2C_HYDRA) += i2c-
>> hydra.o
>> obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o
>>
>> # Embedded system I2C/SMBus host controller drivers
>> +obj-$(CONFIG_I2C_ASPEED) += i2c-aspeed.o
>> obj-$(CONFIG_I2C_AT91) += i2c-at91.o
>> obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o
>> obj-$(CONFIG_I2C_AXXIA) += i2c-axxia.o
>> diff --git a/drivers/i2c/busses/i2c-aspeed.c
>> b/drivers/i2c/busses/i2c-aspeed.c
>> new file mode 100644
>> index 000000000000..a04021e3b3ab
>> --- /dev/null
>> +++ b/drivers/i2c/busses/i2c-aspeed.c
>> @@ -0,0 +1,681 @@
>> +/*
>> + * Aspeed 24XX/25XX I2C Controller.
>> + *
>> + * Copyright (C) 2012-2017 ASPEED Technology Inc.
>> + * Copyright 2017 IBM Corporation
>> + * Copyright 2017 Google, Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or
>> modify
>> + * it under the terms of the GNU General Public License version 2
>> as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/completion.h>
>> +#include <linux/err.h>
>> +#include <linux/errno.h>
>> +#include <linux/i2c.h>
>> +#include <linux/init.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/irq.h>
>> +#include <linux/irqchip/chained_irq.h>
>> +#include <linux/irqdomain.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +
>> +/* I2C Register */
>> +#define ASPEED_I2C_FUN_CTRL_REG 0x00
>> +#define ASPEED_I2C_AC_TIMING_REG1 0x04
>> +#define ASPEED_I2C_AC_TIMING_REG2 0x08
>> +#define ASPEED_I2C_INTR_CTRL_REG 0x0c
>> +#define ASPEED_I2C_INTR_STS_REG 0x10
>> +#define ASPEED_I2C_CMD_REG 0x14
>> +#define ASPEED_I2C_DEV_ADDR_REG 0x18
>> +#define ASPEED_I2C_BYTE_BUF_REG 0x20
>> +
>> +/* Global Register Definition */
>> +/* 0x00 : I2C Interrupt Status Register */
>> +/* 0x08 : I2C Interrupt Target Assignment */
>> +
>> +/* Device Register Definition */
>> +/* 0x00 : I2CD Function Control Register */
>> +#define ASPEED_I2CD_MULTI_MASTER_DIS BIT(15)
>> +#define ASPEED_I2CD_SDA_DRIVE_1T_EN BIT(8)
>> +#define ASPEED_I2CD_M_SDA_DRIVE_1T_EN BIT(7)
>> +#define ASPEED_I2CD_M_HIGH_SPEED_EN BIT(6)
>> +#define ASPEED_I2CD_MASTER_EN BIT(0)
>> +
>> +/* 0x04 : I2CD Clock and AC Timing Control Register #1 */
>> +#define ASPEED_I2CD_TIME_SCL_HIGH_SHIFT 16
>> +#define ASPEED_I2CD_TIME_SCL_HIGH_MASK GENMAS
>> K(19, 16)
>> +#define ASPEED_I2CD_TIME_SCL_LOW_SHIFT 12
>> +#define ASPEED_I2CD_TIME_SCL_LOW_MASK GENMASK
>> (15, 12)
>> +#define ASPEED_I2CD_TIME_BASE_DIVISOR_MASK GENMASK(3,
>> 0)
>> +#define ASPEED_I2CD_TIME_SCL_REG_MAX GENMASK(
>> 3, 0)
>> +/* 0x08 : I2CD Clock and AC Timing Control Register #2 */
>> +#define ASPEED_NO_TIMEOUT_CTRL 0
>> +
>> +/* 0x0c : I2CD Interrupt Control Register &
>> + * 0x10 : I2CD Interrupt Status Register
>> + *
>> + * These share bit definitions, so use the same values for the
>> enable &
>> + * status bits.
>> + */
>> +#define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT BIT(1
>> 4)
>> +#define ASPEED_I2CD_INTR_BUS_RECOVER_DONE BIT(13)
>> +#define ASPEED_I2CD_INTR_SCL_TIMEOUT BIT(6)
>> +#define ASPEED_I2CD_INTR_ABNORMAL BIT(5)
>> +#define ASPEED_I2CD_INTR_NORMAL_STOP BIT(4)
>> +#define ASPEED_I2CD_INTR_ARBIT_LOSS BIT(3)
>> +#define ASPEED_I2CD_INTR_RX_DONE BIT(2)
>> +#define ASPEED_I2CD_INTR_TX_NAK BIT(1
>> )
>> +#define ASPEED_I2CD_INTR_TX_ACK BIT(0
>> )
>> +#define ASPEED_I2CD_INTR_ERROR
>> \
>> + (ASPEED_I2CD_INTR_ARBIT_LOSS |
>> \
>> + ASPEED_I2CD_INTR_ABNORMAL |
>> \
>> + ASPEED_I2CD_INTR_SCL_TIMEOUT |
>> \
>> + ASPEED_I2CD_INTR_SDA_DL_TIMEOUT)
>> +#define ASPEED_I2CD_INTR_ALL
>> \
>> + (ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |
>> \
>> + ASPEED_I2CD_INTR_BUS_RECOVER_DONE |
>> \
>> + ASPEED_I2CD_INTR_SCL_TIMEOUT |
>> \
>> + ASPEED_I2CD_INTR_ABNORMAL |
>> \
>> + ASPEED_I2CD_INTR_NORMAL_STOP |
>> \
>> + ASPEED_I2CD_INTR_ARBIT_LOSS |
>> \
>> + ASPEED_I2CD_INTR_RX_DONE |
>> \
>> + ASPEED_I2CD_INTR_TX_NAK |
>> \
>> + ASPEED_I2CD_INTR_TX_ACK)
>> +
>> +/* 0x14 : I2CD Command/Status Register */
>> +#define ASPEED_I2CD_SCL_LINE_STS BIT(18)
>> +#define ASPEED_I2CD_SDA_LINE_STS BIT(17)
>> +#define ASPEED_I2CD_BUS_BUSY_STS BIT(16)
>> +#define ASPEED_I2CD_BUS_RECOVER_CMD BIT(11)
>> +
>> +/* Command Bit */
>> +#define ASPEED_I2CD_M_STOP_CMD BIT(5)
>> +#define ASPEED_I2CD_M_S_RX_CMD_LAST BIT(4)
>> +#define ASPEED_I2CD_M_RX_CMD BIT(3)
>> +#define ASPEED_I2CD_S_TX_CMD BIT(2)
>> +#define ASPEED_I2CD_M_TX_CMD BIT(1)
>> +#define ASPEED_I2CD_M_START_CMD BIT(0
>> )
>> +
>> +enum aspeed_i2c_master_state {
>> + ASPEED_I2C_MASTER_START,
>> + ASPEED_I2C_MASTER_TX_FIRST,
>> + ASPEED_I2C_MASTER_TX,
>> + ASPEED_I2C_MASTER_RX_FIRST,
>> + ASPEED_I2C_MASTER_RX,
>> + ASPEED_I2C_MASTER_STOP,
>> + ASPEED_I2C_MASTER_INACTIVE,
>> +};
>> +
>> +struct aspeed_i2c_bus {
>> + struct i2c_adapter adap;
>> + struct device *dev;
>> + void __iomem *base;
>> + /* Synchronizes I/O mem access to base. */
>> + spinlock_t lock;
>> + struct completion cmd_complete;
>> + int irq;
>> + unsigned long parent_clk_frequency;
>> + u32 bus_frequency;
>> + /* Transaction state. */
>> + enum aspeed_i2c_master_state master_state;
>> + struct i2c_msg *msgs;
>> + size_t buf_index;
>> + size_t msgs_index;
>> + size_t msgs_count;
>> + bool send_stop;
>> + int cmd_err;
>> + /* Protected only by i2c_lock_bus */
>> + int master_xfer_result;
>> +};
>> +
>> +static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus);
>> +
>> +static int aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)
>> +{
>> + unsigned long time_left, flags;
>> + int ret = 0;
>> + u32 command;
>> +
>> + spin_lock_irqsave(&bus->lock, flags);
>> + command = readl(bus->base + ASPEED_I2C_CMD_REG);
>> +
>> + if (command & ASPEED_I2CD_SDA_LINE_STS) {
>> + /* Bus is idle: no recovery needed. */
>> + if (command & ASPEED_I2CD_SCL_LINE_STS)
>> + goto out;
>> + dev_dbg(bus->dev, "bus hung (state %x), attempting
>> recovery\n",
>> + command);
>> +
>> + reinit_completion(&bus->cmd_complete);
>> + writel(ASPEED_I2CD_M_STOP_CMD, bus->base +
>> ASPEED_I2C_CMD_REG);
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> +
>> + time_left = wait_for_completion_timeout(
>> + &bus->cmd_complete, bus-
>> >adap.timeout);
>> +
>> + spin_lock_irqsave(&bus->lock, flags);
>> + if (time_left == 0)
>> + goto reset_out;
>> + else if (bus->cmd_err)
>> + goto reset_out;
>> + /* Recovery failed. */
>> + else if (!(readl(bus->base + ASPEED_I2C_CMD_REG) &
>> + ASPEED_I2CD_SCL_LINE_STS))
>> + goto reset_out;
>> + /* Bus error. */
>> + } else {
>> + dev_dbg(bus->dev, "bus hung (state %x), attempting
>> recovery\n",
>> + command);
>> +
>> + reinit_completion(&bus->cmd_complete);
>> + writel(ASPEED_I2CD_BUS_RECOVER_CMD,
>> + bus->base + ASPEED_I2C_CMD_REG);
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> +
>> + time_left = wait_for_completion_timeout(
>> + &bus->cmd_complete, bus-
>> >adap.timeout);
>> +
>> + spin_lock_irqsave(&bus->lock, flags);
>> + if (time_left == 0)
>> + goto reset_out;
>> + else if (bus->cmd_err)
>> + goto reset_out;
>> + /* Recovery failed. */
>> + else if (!(readl(bus->base + ASPEED_I2C_CMD_REG) &
>> + ASPEED_I2CD_SDA_LINE_STS))
>> + goto reset_out;
>> + }
>> +
>> +out:
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> +
>> + return ret;
>> +
>> +reset_out:
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> +
>> + return aspeed_i2c_reset(bus);
>> +}
>> +
>> +/* precondition: bus.lock has been acquired. */
>> +static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
>> +{
>> + u32 command = ASPEED_I2CD_M_START_CMD |
>> ASPEED_I2CD_M_TX_CMD;
>> + struct i2c_msg *msg = &bus->msgs[bus->msgs_index];
>> + u8 slave_addr = msg->addr << 1;
>> +
>> + bus->master_state = ASPEED_I2C_MASTER_START;
>> + bus->buf_index = 0;
>> +
>> + if (msg->flags & I2C_M_RD) {
>> + slave_addr |= 1;
>> + command |= ASPEED_I2CD_M_RX_CMD;
>> + /* Need to let the hardware know to NACK after RX.
>> */
>> + if (msg->len == 1 && !(msg->flags & I2C_M_RECV_LEN))
>> + command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
>> + }
>> +
>> + writel(slave_addr, bus->base + ASPEED_I2C_BYTE_BUF_REG);
>> + writel(command, bus->base + ASPEED_I2C_CMD_REG);
>> +}
>> +
>> +/* precondition: bus.lock has been acquired. */
>> +static void aspeed_i2c_do_stop(struct aspeed_i2c_bus *bus)
>> +{
>> + bus->master_state = ASPEED_I2C_MASTER_STOP;
>> + writel(ASPEED_I2CD_M_STOP_CMD, bus->base +
>> ASPEED_I2C_CMD_REG);
>> +}
>> +
>> +/* precondition: bus.lock has been acquired. */
>> +static void aspeed_i2c_next_msg_or_stop(struct aspeed_i2c_bus *bus)
>> +{
>> + if (bus->msgs_index + 1 < bus->msgs_count) {
>> + bus->msgs_index++;
>> + aspeed_i2c_do_start(bus);
>> + } else {
>> + aspeed_i2c_do_stop(bus);
>> + }
>> +}
>> +
>> +static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>> +{
>> + u32 irq_status, status_ack = 0, command = 0;
>> + struct i2c_msg *msg;
>> + u8 recv_byte;
>> +
>> + spin_lock(&bus->lock);
>> + irq_status = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
>> + /* Ack all interrupt bits. */
>> + writel(irq_status, bus->base + ASPEED_I2C_INTR_STS_REG);
>> +
>> + if (irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE) {
>> + bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> + status_ack |= ASPEED_I2CD_INTR_BUS_RECOVER_DONE;
>> + goto out_complete;
>> + }
>> +
>> + /*
>> + * We encountered an interrupt that reports an error: the
>> hardware
>> + * should clear the command queue effectively taking us back
>> to the
>> + * INACTIVE state.
>> + */
>> + if (irq_status & ASPEED_I2CD_INTR_ERROR) {
>> + dev_dbg(bus->dev, "received error interrupt:
>> 0x%08x",
>> + irq_status);
>> + bus->cmd_err = -EIO;
>> + bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> + goto out_complete;
>> + }
>> +
>> + /* We are in an invalid state; reset bus to a known state.
>> */
>> + if (!bus->msgs && bus->master_state !=
>> ASPEED_I2C_MASTER_STOP) {
>> + dev_err(bus->dev, "bus in unknown state");
>> + bus->cmd_err = -EIO;
>> + aspeed_i2c_do_stop(bus);
>> + goto out_no_complete;
>> + }
>> + msg = &bus->msgs[bus->msgs_index];
>> +
>> + /*
>> + * START is a special case because we still have to handle a
>> subsequent
>> + * TX or RX immediately after we handle it, so we handle it
>> here and
>> + * then update the state and handle the new state below.
>> + */
>> + if (bus->master_state == ASPEED_I2C_MASTER_START) {
>> + if (unlikely(!(irq_status &
>> ASPEED_I2CD_INTR_TX_ACK))) {
>> + pr_devel("no slave present at %02x", msg-
>> >addr);
>> + status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>> + goto error_and_stop;
>> + }
>> + status_ack |= ASPEED_I2CD_INTR_TX_ACK;
>> + if (msg->len == 0) { /* SMBUS_QUICK */
>> + aspeed_i2c_do_stop(bus);
>> + goto out_no_complete;
>> + }
>> + if (msg->flags & I2C_M_RD)
>> + bus->master_state =
>> ASPEED_I2C_MASTER_RX_FIRST;
>> + else
>> + bus->master_state =
>> ASPEED_I2C_MASTER_TX_FIRST;
>> + }
>> +
>> + switch (bus->master_state) {
>> + case ASPEED_I2C_MASTER_TX:
>> + if (unlikely(irq_status & ASPEED_I2CD_INTR_TX_NAK))
>> {
>> + dev_dbg(bus->dev, "slave NACKed TX");
>> + status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>> + goto error_and_stop;
>> + } else if (unlikely(!(irq_status &
>> ASPEED_I2CD_INTR_TX_ACK))) {
>> + dev_err(bus->dev, "slave failed to ACK TX");
>> + goto error_and_stop;
>> + }
>> + status_ack |= ASPEED_I2CD_INTR_TX_ACK;
>> + /* fallthrough intended */
>> + case ASPEED_I2C_MASTER_TX_FIRST:
>> + if (bus->buf_index < msg->len) {
>> + bus->master_state = ASPEED_I2C_MASTER_TX;
>> + writel(msg->buf[bus->buf_index++],
>> + bus->base + ASPEED_I2C_BYTE_BUF_REG);
>> + writel(ASPEED_I2CD_M_TX_CMD,
>> + bus->base + ASPEED_I2C_CMD_REG);
>> + } else {
>> + aspeed_i2c_next_msg_or_stop(bus);
>> + }
>> + goto out_no_complete;
>> + case ASPEED_I2C_MASTER_RX_FIRST:
>> + /* RX may not have completed yet (only address
>> cycle) */
>> + if (!(irq_status & ASPEED_I2CD_INTR_RX_DONE))
>> + goto out_no_complete;
>> + /* fallthrough intended */
>> + case ASPEED_I2C_MASTER_RX:
>> + if (unlikely(!(irq_status &
>> ASPEED_I2CD_INTR_RX_DONE))) {
>> + dev_err(bus->dev, "master failed to RX");
>> + goto error_and_stop;
>> + }
>> + status_ack |= ASPEED_I2CD_INTR_RX_DONE;
>> +
>> + recv_byte = readl(bus->base +
>> ASPEED_I2C_BYTE_BUF_REG) >> 8;
>> + msg->buf[bus->buf_index++] = recv_byte;
>> +
>> + if (msg->flags & I2C_M_RECV_LEN) {
>> + if (unlikely(recv_byte >
>> I2C_SMBUS_BLOCK_MAX)) {
>> + bus->cmd_err = -EPROTO;
>> + aspeed_i2c_do_stop(bus);
>> + goto out_no_complete;
>> + }
>> + msg->len = recv_byte +
>> + ((msg->flags &
>> I2C_CLIENT_PEC) ? 2 : 1);
>> + msg->flags &= ~I2C_M_RECV_LEN;
>> + }
>> +
>> + if (bus->buf_index < msg->len) {
>> + bus->master_state = ASPEED_I2C_MASTER_RX;
>> + command = ASPEED_I2CD_M_RX_CMD;
>> + if (bus->buf_index + 1 == msg->len)
>> + command |=
>> ASPEED_I2CD_M_S_RX_CMD_LAST;
>> + writel(command, bus->base +
>> ASPEED_I2C_CMD_REG);
>> + } else {
>> + aspeed_i2c_next_msg_or_stop(bus);
>> + }
>> + goto out_no_complete;
>> + case ASPEED_I2C_MASTER_STOP:
>> + if (unlikely(!(irq_status &
>> ASPEED_I2CD_INTR_NORMAL_STOP))) {
>> + dev_err(bus->dev, "master failed to STOP");
>> + bus->cmd_err = -EIO;
>> + /* Do not STOP as we have already tried. */
>> + } else {
>> + status_ack |= ASPEED_I2CD_INTR_NORMAL_STOP;
>> + }
>> +
>> + bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> + goto out_complete;
>> + case ASPEED_I2C_MASTER_INACTIVE:
>> + dev_err(bus->dev,
>> + "master received interrupt 0x%08x, but is
>> inactive",
>> + irq_status);
>> + bus->cmd_err = -EIO;
>> + /* Do not STOP as we should be inactive. */
>> + goto out_complete;
>> + default:
>> + WARN(1, "unknown master state\n");
>> + bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
>> + bus->cmd_err = -EIO;
>> + goto out_complete;
>> + }
>> +error_and_stop:
>> + bus->cmd_err = -EIO;
>> + aspeed_i2c_do_stop(bus);
>> + goto out_no_complete;
>> +out_complete:
>> + bus->msgs = NULL;
>> + if (bus->cmd_err)
>> + bus->master_xfer_result = bus->cmd_err;
>> + else
>> + bus->master_xfer_result = bus->msgs_index + 1;
>> + complete(&bus->cmd_complete);
>> +out_no_complete:
>> + if (irq_status != status_ack)
>> + dev_err(bus->dev,
>> + "irq handled != irq. expected 0x%08x, but
>> was 0x%08x\n",
>> + irq_status, status_ack);
>> + spin_unlock(&bus->lock);
>> + return !!irq_status;
>> +}
>> +
>> +static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
>> +{
>> + struct aspeed_i2c_bus *bus = dev_id;
>> +
>> + if (aspeed_i2c_master_irq(bus))
>> + return IRQ_HANDLED;
>> + else
>> + return IRQ_NONE;
>> +}
>> +
>> +static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
>> + struct i2c_msg *msgs, int num)
>> +{
>> + struct aspeed_i2c_bus *bus = adap->algo_data;
>> + unsigned long time_left, flags;
>> + int ret = 0;
>> +
>> + spin_lock_irqsave(&bus->lock, flags);
>> + bus->cmd_err = 0;
>> +
>> + /* If bus is busy, attempt recovery. We assume a single
>> master
>> + * environment.
>> + */
>> + if (readl(bus->base + ASPEED_I2C_CMD_REG) &
>> ASPEED_I2CD_BUS_BUSY_STS) {
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> + ret = aspeed_i2c_recover_bus(bus);
>> + if (ret)
>> + return ret;
>> + spin_lock_irqsave(&bus->lock, flags);
>> + }
>> +
>> + bus->cmd_err = 0;
>> + bus->msgs = msgs;
>> + bus->msgs_index = 0;
>> + bus->msgs_count = num;
>> +
>> + reinit_completion(&bus->cmd_complete);
>> + aspeed_i2c_do_start(bus);
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> +
>> + time_left = wait_for_completion_timeout(&bus->cmd_complete,
>> + bus->adap.timeout);
>> +
>> + if (time_left == 0)
>> + return -ETIMEDOUT;
>> + else
>> + return bus->master_xfer_result;
>> +}
>> +
>> +static u32 aspeed_i2c_functionality(struct i2c_adapter *adap)
>> +{
>> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
>> I2C_FUNC_SMBUS_BLOCK_DATA;
>> +}
>> +
>> +static const struct i2c_algorithm aspeed_i2c_algo = {
>> + .master_xfer = aspeed_i2c_master_xfer,
>> + .functionality = aspeed_i2c_functionality,
>> +};
>> +
>> +static u32 aspeed_i2c_get_clk_reg_val(u32 divisor)
>> +{
>> + u32 base_clk, clk_high, clk_low, tmp;
>> +
>> + /*
>> + * The actual clock frequency of SCL is:
>> + * SCL_freq = APB_freq / (base_freq * (SCL_high +
>> SCL_low))
>> + * = APB_freq / divisor
>> + * where base_freq is a programmable clock divider; its
>> value is
>> + * base_freq = 1 << base_clk
>> + * SCL_high is the number of base_freq clock cycles that SCL
>> stays high
>> + * and SCL_low is the number of base_freq clock cycles that
>> SCL stays
>> + * low for a period of SCL.
>> + * The actual register has a minimum SCL_high and SCL_low
>> minimum of 1;
>> + * thus, they start counting at zero. So
>> + * SCL_high = clk_high + 1
>> + * SCL_low = clk_low + 1
>> + * Thus,
>> + * SCL_freq = APB_freq /
>> + * ((1 << base_clk) * (clk_high + 1 + clk_low
>> + 1))
>> + * The documentation recommends clk_high >= 8 and clk_low >=
>> 7 when
>> + * possible; this last constraint gives us the following
>> solution:
>> + */
>> + base_clk = divisor > 33 ? ilog2((divisor - 1) / 32) + 1 : 0;
>> + tmp = divisor / (1 << base_clk);
>> + clk_high = tmp / 2 + tmp % 2;
>> + clk_low = tmp - clk_high;
>> +
>> + clk_high -= 1;
>> + clk_low -= 1;
>> +
>> + return ((clk_high << ASPEED_I2CD_TIME_SCL_HIGH_SHIFT)
>> + & ASPEED_I2CD_TIME_SCL_HIGH_MASK)
>> + | ((clk_low <<
>> ASPEED_I2CD_TIME_SCL_LOW_SHIFT)
>> + & ASPEED_I2CD_TIME_SCL_LOW_MASK)
>> + | (base_clk &
>> ASPEED_I2CD_TIME_BASE_DIVISOR_MASK);
>> +}
>> +
>> +/* precondition: bus.lock has been acquired. */
>> +static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus)
>> +{
>> + u32 divisor, clk_reg_val;
>> +
>> + divisor = bus->parent_clk_frequency / bus->bus_frequency;
>> + clk_reg_val = aspeed_i2c_get_clk_reg_val(divisor);
>> + writel(clk_reg_val, bus->base + ASPEED_I2C_AC_TIMING_REG1);
>> + writel(ASPEED_NO_TIMEOUT_CTRL, bus->base +
>> ASPEED_I2C_AC_TIMING_REG2);
>> +
>> + return 0;
>> +}
>> +
>> +/* precondition: bus.lock has been acquired. */
>> +static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
>> + struct platform_device *pdev)
>> +{
>> + u32 fun_ctrl_reg = ASPEED_I2CD_MASTER_EN;
>> + int ret;
>> +
>> + /* Disable everything. */
>> + writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG);
>> +
>> + ret = aspeed_i2c_init_clk(bus);
>> + if (ret < 0)
>> + return ret;
>> +
>> + if (!of_property_read_bool(pdev->dev.of_node, "multi-
>> master"))
>> + fun_ctrl_reg |= ASPEED_I2CD_MULTI_MASTER_DIS;
>> +
>> + /* Enable Master Mode */
>> + writel(readl(bus->base + ASPEED_I2C_FUN_CTRL_REG) |
>> fun_ctrl_reg,
>> + bus->base + ASPEED_I2C_FUN_CTRL_REG);
>> +
>> + /* Set interrupt generation of I2C controller */
>> + writel(ASPEED_I2CD_INTR_ALL, bus->base +
>> ASPEED_I2C_INTR_CTRL_REG);
>> +
>> + return 0;
>> +}
>> +
>> +static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus)
>> +{
>> + struct platform_device *pdev = to_platform_device(bus->dev);
>> + unsigned long flags;
>> + int ret;
>> +
>> + spin_lock_irqsave(&bus->lock, flags);
>> +
>> + /* Disable and ack all interrupts. */
>> + writel(0, bus->base + ASPEED_I2C_INTR_CTRL_REG);
>> + writel(0xffffffff, bus->base + ASPEED_I2C_INTR_STS_REG);
>> +
>> + ret = aspeed_i2c_init(bus, pdev);
>> +
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> +
>> + return ret;
>> +}
>> +
>> +static int aspeed_i2c_probe_bus(struct platform_device *pdev)
>> +{
>> + struct aspeed_i2c_bus *bus;
>> + struct clk *parent_clk;
>> + struct resource *res;
>> + int ret;
>> +
>> + bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
>> + if (!bus)
>> + return -ENOMEM;
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + bus->base = devm_ioremap_resource(&pdev->dev, res);
>> + if (IS_ERR(bus->base))
>> + return PTR_ERR(bus->base);
>> +
>> + parent_clk = devm_clk_get(&pdev->dev, NULL);
>> + if (IS_ERR(parent_clk))
>> + return PTR_ERR(parent_clk);
>> + bus->parent_clk_frequency = clk_get_rate(parent_clk);
>> + /* We just need the clock rate, we don't actually use the
>> clk object. */
>> + devm_clk_put(&pdev->dev, parent_clk);
>> +
>> + ret = of_property_read_u32(pdev->dev.of_node,
>> + "bus-frequency", &bus-
>> >bus_frequency);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev,
>> + "Could not read bus-frequency property\n");
>> + bus->bus_frequency = 100000;
>> + }
>> +
>> + /* Initialize the I2C adapter */
>> + spin_lock_init(&bus->lock);
>> + init_completion(&bus->cmd_complete);
>> + bus->adap.owner = THIS_MODULE;
>> + bus->adap.retries = 0;
>> + bus->adap.timeout = 5 * HZ;
>> + bus->adap.algo = &aspeed_i2c_algo;
>> + bus->adap.algo_data = bus;
>> + bus->adap.dev.parent = &pdev->dev;
>> + bus->adap.dev.of_node = pdev->dev.of_node;
>> + strlcpy(bus->adap.name, pdev->name, sizeof(bus->adap.name));
>> +
>> + bus->dev = &pdev->dev;
>> +
>> + /* Clean up any left over interrupt state. */
>> + writel(0, bus->base + ASPEED_I2C_INTR_CTRL_REG);
>> + writel(0xffffffff, bus->base + ASPEED_I2C_INTR_STS_REG);
>> + /*
>> + * bus.lock does not need to be held because the interrupt
>> handler has
>> + * not been enabled yet.
>> + */
>> + ret = aspeed_i2c_init(bus, pdev);
>> + if (ret < 0)
>> + return ret;
>> +
>> + bus->irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
>> + ret = devm_request_irq(&pdev->dev, bus->irq,
>> aspeed_i2c_bus_irq,
>> + 0, dev_name(&pdev->dev), bus);
>> + if (ret < 0)
>> + return ret;
>> +
>> + ret = i2c_add_adapter(&bus->adap);
>> + if (ret < 0)
>> + return ret;
>> +
>> + platform_set_drvdata(pdev, bus);
>> +
>> + dev_info(bus->dev, "i2c bus %d registered, irq %d\n",
>> + bus->adap.nr, bus->irq);
>> +
>> + return 0;
>> +}
>> +
>> +static int aspeed_i2c_remove_bus(struct platform_device *pdev)
>> +{
>> + struct aspeed_i2c_bus *bus = platform_get_drvdata(pdev);
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&bus->lock, flags);
>> +
>> + /* Disable everything. */
>> + writel(0, bus->base + ASPEED_I2C_FUN_CTRL_REG);
>> + writel(0, bus->base + ASPEED_I2C_INTR_CTRL_REG);
>> +
>> + spin_unlock_irqrestore(&bus->lock, flags);
>> +
>> + i2c_del_adapter(&bus->adap);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id aspeed_i2c_bus_of_table[] = {
>> + { .compatible = "aspeed,ast2400-i2c-bus", },
>> + { .compatible = "aspeed,ast2500-i2c-bus", },
>> + { },
>> +};
>> +MODULE_DEVICE_TABLE(of, aspeed_i2c_bus_of_table);
>> +
>> +static struct platform_driver aspeed_i2c_bus_driver = {
>> + .probe = aspeed_i2c_probe_bus,
>> + .remove = aspeed_i2c_remove_bus,
>> + .driver = {
>> + .name = "aspeed-i2c-bus",
>> + .of_match_table = aspeed_i2c_bus_of_table,
>> + },
>> +};
>> +module_platform_driver(aspeed_i2c_bus_driver);
>> +
>> +MODULE_AUTHOR("Brendan Higgins <brendanhigg...@google.com>");
>> +MODULE_DESCRIPTION("Aspeed I2C Bus Driver");
>> +MODULE_LICENSE("GPL v2");
