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i2c: altera: Add Altera I2C Controller driver 

Add driver support for the Altera I2C Controller. The I2C
controller is soft IP for use in FPGAs.

Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Thor Thayer 2017-09-11 16:17:20 -05:00 committed by Wolfram Sang
parent 8f73681616
commit 0560ad5762
4 changed files with 527 additions and 0 deletions
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5
MAINTAINERS
View File

@ -644,6 +644,11 @@ ALPS PS/2 TOUCHPAD DRIVER
R: Pali Rohár <pali.rohar@gmail.com>
F: drivers/input/mouse/alps.*
ALTERA I2C CONTROLLER DRIVER
M: Thor Thayer <thor.thayer@linux.intel.com>
S: Maintained
F: drivers/i2c/busses/i2c-altera.c
ALTERA MAILBOX DRIVER
M: Ley Foon Tan <lftan@altera.com>
L: nios2-dev@lists.rocketboards.org (moderated for non-subscribers)

10
drivers/i2c/busses/Kconfig
View File

@ -336,6 +336,16 @@ config I2C_POWERMAC
comment "I2C system bus drivers (mostly embedded / system-on-chip)"
config I2C_ALTERA
tristate "Altera Soft IP I2C"
depends on (ARCH_SOCFPGA || NIOS2) && OF
help
If you say yes to this option, support will be included for the
Altera Soft IP I2C interfaces on SoCFPGA and Nios2 architectures.
This driver can also be built as a module. If so, the module
will be called i2c-altera.
config I2C_ASPEED
tristate "Aspeed I2C Controller"
depends on ARCH_ASPEED || COMPILE_TEST

1
drivers/i2c/busses/Makefile
View File

@ -30,6 +30,7 @@ obj-$(CONFIG_I2C_HYDRA) += i2c-hydra.o
obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o
# Embedded system I2C/SMBus host controller drivers
obj-$(CONFIG_I2C_ALTERA) += i2c-altera.o
obj-$(CONFIG_I2C_ASPEED) += i2c-aspeed.o
obj-$(CONFIG_I2C_AT91) += i2c-at91.o
obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o

511
drivers/i2c/busses/i2c-altera.c Normal file
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@ -0,0 +1,511 @@
/*
* Copyright Intel Corporation (C) 2017.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*
* Based on the i2c-axxia.c driver.
*/
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/iopoll.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#define ALTR_I2C_TFR_CMD 0x00 /* Transfer Command register */
#define ALTR_I2C_TFR_CMD_STA BIT(9) /* send START before byte */
#define ALTR_I2C_TFR_CMD_STO BIT(8) /* send STOP after byte */
#define ALTR_I2C_TFR_CMD_RW_D BIT(0) /* Direction of transfer */
#define ALTR_I2C_RX_DATA 0x04 /* RX data FIFO register */
#define ALTR_I2C_CTRL 0x08 /* Control register */
#define ALTR_I2C_CTRL_RXT_SHFT 4 /* RX FIFO Threshold */
#define ALTR_I2C_CTRL_TCT_SHFT 2 /* TFER CMD FIFO Threshold */
#define ALTR_I2C_CTRL_BSPEED BIT(1) /* Bus Speed (1=Fast) */
#define ALTR_I2C_CTRL_EN BIT(0) /* Enable Core (1=Enable) */
#define ALTR_I2C_ISER 0x0C /* Interrupt Status Enable register */
#define ALTR_I2C_ISER_RXOF_EN BIT(4) /* Enable RX OVERFLOW IRQ */
#define ALTR_I2C_ISER_ARB_EN BIT(3) /* Enable ARB LOST IRQ */
#define ALTR_I2C_ISER_NACK_EN BIT(2) /* Enable NACK DET IRQ */
#define ALTR_I2C_ISER_RXRDY_EN BIT(1) /* Enable RX Ready IRQ */
#define ALTR_I2C_ISER_TXRDY_EN BIT(0) /* Enable TX Ready IRQ */
#define ALTR_I2C_ISR 0x10 /* Interrupt Status register */
#define ALTR_I2C_ISR_RXOF BIT(4) /* RX OVERFLOW IRQ */
#define ALTR_I2C_ISR_ARB BIT(3) /* ARB LOST IRQ */
#define ALTR_I2C_ISR_NACK BIT(2) /* NACK DET IRQ */
#define ALTR_I2C_ISR_RXRDY BIT(1) /* RX Ready IRQ */
#define ALTR_I2C_ISR_TXRDY BIT(0) /* TX Ready IRQ */
#define ALTR_I2C_STATUS 0x14 /* Status register */
#define ALTR_I2C_STAT_CORE BIT(0) /* Core Status (0=idle) */
#define ALTR_I2C_TC_FIFO_LVL 0x18 /* Transfer FIFO LVL register */
#define ALTR_I2C_RX_FIFO_LVL 0x1C /* Receive FIFO LVL register */
#define ALTR_I2C_SCL_LOW 0x20 /* SCL low count register */
#define ALTR_I2C_SCL_HIGH 0x24 /* SCL high count register */
#define ALTR_I2C_SDA_HOLD 0x28 /* SDA hold count register */
#define ALTR_I2C_ALL_IRQ (ALTR_I2C_ISR_RXOF | ALTR_I2C_ISR_ARB | \
ALTR_I2C_ISR_NACK | ALTR_I2C_ISR_RXRDY | \
ALTR_I2C_ISR_TXRDY)
#define ALTR_I2C_THRESHOLD 0 /* IRQ Threshold at 1 element */
#define ALTR_I2C_DFLT_FIFO_SZ 4
#define ALTR_I2C_TIMEOUT 100000 /* 100ms */
#define ALTR_I2C_XFER_TIMEOUT (msecs_to_jiffies(250))
/**
* altr_i2c_dev - I2C device context
* @base: pointer to register struct
* @msg: pointer to current message
* @msg_len: number of bytes transferred in msg
* @msg_err: error code for completed message
* @msg_complete: xfer completion object
* @dev: device reference
* @adapter: core i2c abstraction
* @i2c_clk: clock reference for i2c input clock
* @bus_clk_rate: current i2c bus clock rate
* @buf: ptr to msg buffer for easier use.
* @fifo_size: size of the FIFO passed in.
* @isr_mask: cached copy of local ISR enables.
* @isr_status: cached copy of local ISR status.
* @lock: spinlock for IRQ synchronization.
*/
struct altr_i2c_dev {
void __iomem *base;
struct i2c_msg *msg;
size_t msg_len;
int msg_err;
struct completion msg_complete;
struct device *dev;
struct i2c_adapter adapter;
struct clk *i2c_clk;
u32 bus_clk_rate;
u8 *buf;
u32 fifo_size;
u32 isr_mask;
u32 isr_status;
spinlock_t lock; /* IRQ synchronization */
};
static void
altr_i2c_int_enable(struct altr_i2c_dev *idev, u32 mask, bool enable)
{
unsigned long flags;
u32 int_en;
spin_lock_irqsave(&idev->lock, flags);
int_en = readl(idev->base + ALTR_I2C_ISER);
if (enable)
idev->isr_mask = int_en | mask;
else
idev->isr_mask = int_en & ~mask;
writel(idev->isr_mask, idev->base + ALTR_I2C_ISER);
spin_unlock_irqrestore(&idev->lock, flags);
}
static void altr_i2c_int_clear(struct altr_i2c_dev *idev, u32 mask)
{
u32 int_en = readl(idev->base + ALTR_I2C_ISR);
writel(int_en | mask, idev->base + ALTR_I2C_ISR);
}
static void altr_i2c_core_disable(struct altr_i2c_dev *idev)
{
u32 tmp = readl(idev->base + ALTR_I2C_CTRL);
writel(tmp & ~ALTR_I2C_CTRL_EN, idev->base + ALTR_I2C_CTRL);
}
static void altr_i2c_core_enable(struct altr_i2c_dev *idev)
{
u32 tmp = readl(idev->base + ALTR_I2C_CTRL);
writel(tmp | ALTR_I2C_CTRL_EN, idev->base + ALTR_I2C_CTRL);
}
static void altr_i2c_reset(struct altr_i2c_dev *idev)
{
altr_i2c_core_disable(idev);
altr_i2c_core_enable(idev);
}
static inline void altr_i2c_stop(struct altr_i2c_dev *idev)
{
writel(ALTR_I2C_TFR_CMD_STO, idev->base + ALTR_I2C_TFR_CMD);
}
static void altr_i2c_init(struct altr_i2c_dev *idev)
{
u32 divisor = clk_get_rate(idev->i2c_clk) / idev->bus_clk_rate;
u32 clk_mhz = clk_get_rate(idev->i2c_clk) / 1000000;
u32 tmp = (ALTR_I2C_THRESHOLD << ALTR_I2C_CTRL_RXT_SHFT) |
(ALTR_I2C_THRESHOLD << ALTR_I2C_CTRL_TCT_SHFT);
u32 t_high, t_low;
if (idev->bus_clk_rate <= 100000) {
tmp &= ~ALTR_I2C_CTRL_BSPEED;
/* Standard mode SCL 50/50 */
t_high = divisor * 1 / 2;
t_low = divisor * 1 / 2;
} else {
tmp |= ALTR_I2C_CTRL_BSPEED;
/* Fast mode SCL 33/66 */
t_high = divisor * 1 / 3;
t_low = divisor * 2 / 3;
}
writel(tmp, idev->base + ALTR_I2C_CTRL);
dev_dbg(idev->dev, "rate=%uHz per_clk=%uMHz -> ratio=1:%u\n",
idev->bus_clk_rate, clk_mhz, divisor);
/* Reset controller */
altr_i2c_reset(idev);
/* SCL High Time */
writel(t_high, idev->base + ALTR_I2C_SCL_HIGH);
/* SCL Low Time */
writel(t_low, idev->base + ALTR_I2C_SCL_LOW);
/* SDA Hold Time, 300ns */
writel(div_u64(300 * clk_mhz, 1000), idev->base + ALTR_I2C_SDA_HOLD);
/* Mask all master interrupt bits */
altr_i2c_int_enable(idev, ALTR_I2C_ALL_IRQ, false);
}
/**
* altr_i2c_transfer - On the last byte to be transmitted, send
* a Stop bit on the last byte.
*/
static void altr_i2c_transfer(struct altr_i2c_dev *idev, u32 data)
{
/* On the last byte to be transmitted, send STOP */
if (idev->msg_len == 1)
data |= ALTR_I2C_TFR_CMD_STO;
if (idev->msg_len > 0)
writel(data, idev->base + ALTR_I2C_TFR_CMD);
}
/**
* altr_i2c_empty_rx_fifo - Fetch data from RX FIFO until end of
* transfer. Send a Stop bit on the last byte.
*/
static void altr_i2c_empty_rx_fifo(struct altr_i2c_dev *idev)
{
size_t rx_fifo_avail = readl(idev->base + ALTR_I2C_RX_FIFO_LVL);
int bytes_to_transfer = min(rx_fifo_avail, idev->msg_len);
while (bytes_to_transfer-- > 0) {
*idev->buf++ = readl(idev->base + ALTR_I2C_RX_DATA);
idev->msg_len--;
altr_i2c_transfer(idev, 0);
}
}
/**
* altr_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer.
* @return: Number of bytes left to transfer.
*/
static int altr_i2c_fill_tx_fifo(struct altr_i2c_dev *idev)
{
size_t tx_fifo_avail = idev->fifo_size - readl(idev->base +
ALTR_I2C_TC_FIFO_LVL);
int bytes_to_transfer = min(tx_fifo_avail, idev->msg_len);
int ret = idev->msg_len - bytes_to_transfer;
while (bytes_to_transfer-- > 0) {
altr_i2c_transfer(idev, *idev->buf++);
idev->msg_len--;
}
return ret;
}
static irqreturn_t altr_i2c_isr_quick(int irq, void *_dev)
{
struct altr_i2c_dev *idev = _dev;
irqreturn_t ret = IRQ_HANDLED;
/* Read IRQ status but only interested in Enabled IRQs. */
idev->isr_status = readl(idev->base + ALTR_I2C_ISR) & idev->isr_mask;
if (idev->isr_status)
ret = IRQ_WAKE_THREAD;
return ret;
}
static irqreturn_t altr_i2c_isr(int irq, void *_dev)
{
int ret;
bool read, finish = false;
struct altr_i2c_dev *idev = _dev;
u32 status = idev->isr_status;
if (!idev->msg) {
dev_warn(idev->dev, "unexpected interrupt\n");
altr_i2c_int_clear(idev, ALTR_I2C_ALL_IRQ);
return IRQ_HANDLED;
}
read = (idev->msg->flags & I2C_M_RD) != 0;
/* handle Lost Arbitration */
if (unlikely(status & ALTR_I2C_ISR_ARB)) {
altr_i2c_int_clear(idev, ALTR_I2C_ISR_ARB);
idev->msg_err = -EAGAIN;
finish = true;
} else if (unlikely(status & ALTR_I2C_ISR_NACK)) {
dev_dbg(idev->dev, "Could not get ACK\n");
idev->msg_err = -ENXIO;
altr_i2c_int_clear(idev, ALTR_I2C_ISR_NACK);
altr_i2c_stop(idev);
finish = true;
} else if (read && unlikely(status & ALTR_I2C_ISR_RXOF)) {
/* handle RX FIFO Overflow */
altr_i2c_empty_rx_fifo(idev);
altr_i2c_int_clear(idev, ALTR_I2C_ISR_RXRDY);
altr_i2c_stop(idev);
dev_err(idev->dev, "RX FIFO Overflow\n");
finish = true;
} else if (read && (status & ALTR_I2C_ISR_RXRDY)) {
/* RX FIFO needs service? */
altr_i2c_empty_rx_fifo(idev);
altr_i2c_int_clear(idev, ALTR_I2C_ISR_RXRDY);
if (!idev->msg_len)
finish = true;
} else if (!read && (status & ALTR_I2C_ISR_TXRDY)) {
/* TX FIFO needs service? */
altr_i2c_int_clear(idev, ALTR_I2C_ISR_TXRDY);
if (idev->msg_len > 0)
altr_i2c_fill_tx_fifo(idev);
else
finish = true;
} else {
dev_warn(idev->dev, "Unexpected interrupt: 0x%x\n", status);
altr_i2c_int_clear(idev, ALTR_I2C_ALL_IRQ);
}
if (finish) {
/* Wait for the Core to finish */
ret = readl_poll_timeout_atomic(idev->base + ALTR_I2C_STATUS,
status,
!(status & ALTR_I2C_STAT_CORE),
1, ALTR_I2C_TIMEOUT);
if (ret)
dev_err(idev->dev, "message timeout\n");
altr_i2c_int_enable(idev, ALTR_I2C_ALL_IRQ, false);
altr_i2c_int_clear(idev, ALTR_I2C_ALL_IRQ);
complete(&idev->msg_complete);
dev_dbg(idev->dev, "Message Complete\n");
}
return IRQ_HANDLED;
}
static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg)
{
u32 imask = ALTR_I2C_ISR_RXOF | ALTR_I2C_ISR_ARB | ALTR_I2C_ISR_NACK;
unsigned long time_left;
u32 value;
u8 addr = i2c_8bit_addr_from_msg(msg);
idev->msg = msg;
idev->msg_len = msg->len;
idev->buf = msg->buf;
idev->msg_err = 0;
reinit_completion(&idev->msg_complete);
altr_i2c_core_enable(idev);
/* Make sure RX FIFO is empty */
do {
readl(idev->base + ALTR_I2C_RX_DATA);
} while (readl(idev->base + ALTR_I2C_RX_FIFO_LVL));
writel(ALTR_I2C_TFR_CMD_STA | addr, idev->base + ALTR_I2C_TFR_CMD);
if ((msg->flags & I2C_M_RD) != 0) {
imask |= ALTR_I2C_ISER_RXOF_EN | ALTR_I2C_ISER_RXRDY_EN;
altr_i2c_int_enable(idev, imask, true);
/* write the first byte to start the RX */
altr_i2c_transfer(idev, 0);
} else {
imask |= ALTR_I2C_ISR_TXRDY;
altr_i2c_int_enable(idev, imask, true);
altr_i2c_fill_tx_fifo(idev);
}
time_left = wait_for_completion_timeout(&idev->msg_complete,
ALTR_I2C_XFER_TIMEOUT);
altr_i2c_int_enable(idev, imask, false);
value = readl(idev->base + ALTR_I2C_STATUS) & ALTR_I2C_STAT_CORE;
if (value)
dev_err(idev->dev, "Core Status not IDLE...\n");
if (time_left == 0) {
idev->msg_err = -ETIMEDOUT;
dev_dbg(idev->dev, "Transaction timed out.\n");
}
altr_i2c_core_disable(idev);
return idev->msg_err;
}
static int
altr_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
struct altr_i2c_dev *idev = i2c_get_adapdata(adap);
int i, ret;
for (i = 0; i < num; i++) {
ret = altr_i2c_xfer_msg(idev, msgs++);
if (ret)
return ret;
}
return num;
}
static u32 altr_i2c_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}
static const struct i2c_algorithm altr_i2c_algo = {
.master_xfer = altr_i2c_xfer,
.functionality = altr_i2c_func,
};
static int altr_i2c_probe(struct platform_device *pdev)
{
struct altr_i2c_dev *idev = NULL;
struct resource *res;
int irq, ret;
u32 val;
idev = devm_kzalloc(&pdev->dev, sizeof(*idev), GFP_KERNEL);
if (!idev)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
idev->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(idev->base))
return PTR_ERR(idev->base);
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
dev_err(&pdev->dev, "missing interrupt resource\n");
return irq;
}
idev->i2c_clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(idev->i2c_clk)) {
dev_err(&pdev->dev, "missing clock\n");
return PTR_ERR(idev->i2c_clk);
}
idev->dev = &pdev->dev;
init_completion(&idev->msg_complete);
spin_lock_init(&idev->lock);
val = device_property_read_u32(idev->dev, "fifo-size",
&idev->fifo_size);
if (val) {
dev_err(&pdev->dev, "FIFO size set to default of %d\n",
ALTR_I2C_DFLT_FIFO_SZ);
idev->fifo_size = ALTR_I2C_DFLT_FIFO_SZ;
}
val = device_property_read_u32(idev->dev, "clock-frequency",
&idev->bus_clk_rate);
if (val) {
dev_err(&pdev->dev, "Default to 100kHz\n");
idev->bus_clk_rate = 100000; /* default clock rate */
}
if (idev->bus_clk_rate > 400000) {
dev_err(&pdev->dev, "invalid clock-frequency %d\n",
idev->bus_clk_rate);
return -EINVAL;
}
ret = devm_request_threaded_irq(&pdev->dev, irq, altr_i2c_isr_quick,
altr_i2c_isr, IRQF_ONESHOT,
pdev->name, idev);
if (ret) {
dev_err(&pdev->dev, "failed to claim IRQ %d\n", irq);
return ret;
}
ret = clk_prepare_enable(idev->i2c_clk);
if (ret) {
dev_err(&pdev->dev, "failed to enable clock\n");
return ret;
}
altr_i2c_init(idev);
i2c_set_adapdata(&idev->adapter, idev);
strlcpy(idev->adapter.name, pdev->name, sizeof(idev->adapter.name));
idev->adapter.owner = THIS_MODULE;
idev->adapter.algo = &altr_i2c_algo;
idev->adapter.dev.parent = &pdev->dev;
idev->adapter.dev.of_node = pdev->dev.of_node;
platform_set_drvdata(pdev, idev);
ret = i2c_add_adapter(&idev->adapter);
if (ret) {
clk_disable_unprepare(idev->i2c_clk);
return ret;
}
dev_info(&pdev->dev, "Altera SoftIP I2C Probe Complete\n");
return 0;
}
static int altr_i2c_remove(struct platform_device *pdev)
{
struct altr_i2c_dev *idev = platform_get_drvdata(pdev);
clk_disable_unprepare(idev->i2c_clk);
i2c_del_adapter(&idev->adapter);
return 0;
}
/* Match table for of_platform binding */
static const struct of_device_id altr_i2c_of_match[] = {
{ .compatible = "altr,softip-i2c-v1.0" },
{},
};
MODULE_DEVICE_TABLE(of, altr_i2c_of_match);
static struct platform_driver altr_i2c_driver = {
.probe = altr_i2c_probe,
.remove = altr_i2c_remove,
.driver = {
.name = "altera-i2c",
.of_match_table = altr_i2c_of_match,
},
};
module_platform_driver(altr_i2c_driver);
MODULE_DESCRIPTION("Altera Soft IP I2C bus driver");
MODULE_AUTHOR("Thor Thayer <thor.thayer@linux.intel.com>");
MODULE_LICENSE("GPL v2");