[PATCHv3 4/4] i2c: altera: Add Altera I2C Controller driver
thor.thayer at linux.intel.com
thor.thayer at linux.intel.com
Fri Jun 2 16:52:39 PDT 2017
From: Thor Thayer <thor.thayer at linux.intel.com>
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 at linux.intel.com>
---
v2 Remove altr, from fifo-size to agree with bindings.
Change compatible string to "altr,softip-i2c"
v3 Add version to compatible string "altr,softip-i2c-v1.0"
---
drivers/i2c/busses/Kconfig | 10 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-altera.c | 509 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 520 insertions(+)
create mode 100644 drivers/i2c/busses/i2c-altera.c
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 144cbad..981ea48 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_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_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 30b6085..4eb5c82 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-$(CONFIG_I2C_ALTERA) += i2c-altera.o
obj-$(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-altera.c b/drivers/i2c/busses/i2c-altera.c
new file mode 100644
index 0000000..0c7717d
--- /dev/null
+++ b/drivers/i2c/busses/i2c-altera.c
@@ -0,0 +1,509 @@
+/*
+ * 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/init.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 100
+#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.
+ */
+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;
+ unsigned int fifo_size;
+};
+
+static void i2c_int_disable(struct altr_i2c_dev *idev, u32 mask)
+{
+ u32 int_en = readl(idev->base + ALTR_I2C_ISER);
+
+ writel(int_en & ~mask, idev->base + ALTR_I2C_ISER);
+}
+
+static void i2c_int_enable(struct altr_i2c_dev *idev, u32 mask)
+{
+ u32 int_en = readl(idev->base + ALTR_I2C_ISER);
+
+ writel(int_en | mask, idev->base + ALTR_I2C_ISER);
+}
+
+static void 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 void altr_i2c_recover(struct altr_i2c_dev *idev)
+{
+ altr_i2c_reset(idev);
+ /* Clock start bit + 8 bits + stop bit out */
+ writel(ALTR_I2C_TFR_CMD_STA | ALTR_I2C_TFR_CMD_STO,
+ idev->base + ALTR_I2C_TFR_CMD);
+ altr_i2c_reset(idev);
+
+ i2c_recover_bus(&idev->adapter);
+}
+
+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 */
+ i2c_int_disable(idev, ~0);
+}
+
+static int i2c_m_rd(const struct i2c_msg *msg)
+{
+ return (msg->flags & I2C_M_RD) != 0;
+}
+
+/**
+ * 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);
+ if (idev->msg_len == 1)
+ altr_i2c_stop(idev);
+ else
+ writel(0, idev->base + ALTR_I2C_TFR_CMD);
+
+ idev->msg_len--;
+ }
+}
+
+/**
+ * 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) {
+ if (idev->msg_len == 1)
+ writel(ALTR_I2C_TFR_CMD_STO | *idev->buf++,
+ idev->base + ALTR_I2C_TFR_CMD);
+ else
+ writel(*idev->buf++, idev->base + ALTR_I2C_TFR_CMD);
+ idev->msg_len--;
+ }
+
+ return ret;
+}
+
+/**
+ * altr_i2c_wait_for_core_idle - After TX, check core idle for all bytes TX.
+ * @return: 0 on success or -ETIMEDOUT on timeout.
+ */
+static int altr_i2c_wait_for_core_idle(struct altr_i2c_dev *idev)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(ALTR_I2C_TIMEOUT);
+
+ do {
+ if (time_after(jiffies, timeout)) {
+ dev_err(idev->dev, "Core Idle timeout\n");
+ return -ETIMEDOUT;
+ }
+ } while (readl(idev->base + ALTR_I2C_STATUS) & ALTR_I2C_STAT_CORE);
+
+ return 0;
+}
+
+static irqreturn_t altr_i2c_isr(int irq, void *_dev)
+{
+ struct altr_i2c_dev *idev = _dev;
+ /* Read IRQ status but only interested in Enabled IRQs. */
+ u32 status = readl(idev->base + ALTR_I2C_ISR) &
+ readl(idev->base + ALTR_I2C_ISER);
+
+ if (!idev->msg) {
+ dev_warn(idev->dev, "unexpected interrupt\n");
+ goto out;
+ }
+
+ /* handle Lost Arbitration */
+ if (unlikely(status & ALTR_I2C_ISR_ARB)) {
+ dev_err(idev->dev, "%s: arbitration lost\n", __func__);
+ i2c_int_clear(idev, ALTR_I2C_ISR_ARB);
+ idev->msg_err = -EAGAIN;
+ goto complete;
+ }
+
+ if (unlikely(status & ALTR_I2C_ISR_NACK)) {
+ dev_dbg(idev->dev, "%s: could not get ACK\n", __func__);
+ idev->msg_err = -ENXIO;
+ i2c_int_clear(idev, ALTR_I2C_ISR_NACK);
+ altr_i2c_stop(idev);
+ goto complete;
+ }
+
+ /* handle RX FIFO Overflow */
+ if (i2c_m_rd(idev->msg) && unlikely(status & ALTR_I2C_ISR_RXOF)) {
+ altr_i2c_empty_rx_fifo(idev);
+ i2c_int_clear(idev, ALTR_I2C_ISR_RXRDY);
+ altr_i2c_stop(idev);
+ dev_err(idev->dev, "%s: RX FIFO Overflow\n", __func__);
+ goto complete;
+ }
+
+ /* RX FIFO needs service? */
+ if (i2c_m_rd(idev->msg) && (status & ALTR_I2C_ISR_RXRDY)) {
+ altr_i2c_empty_rx_fifo(idev);
+ i2c_int_clear(idev, ALTR_I2C_ISR_RXRDY);
+ if (!idev->msg_len)
+ goto complete;
+
+ goto out;
+ }
+
+ /* TX FIFO needs service? */
+ if (!i2c_m_rd(idev->msg) && (status & ALTR_I2C_ISR_TXRDY)) {
+ i2c_int_clear(idev, ALTR_I2C_ISR_TXRDY);
+ if (!altr_i2c_fill_tx_fifo(idev))
+ goto complete;
+
+ goto out;
+ }
+
+complete:
+ dev_dbg(idev->dev, "%s: Message Complete\n", __func__);
+ if (altr_i2c_wait_for_core_idle(idev))
+ dev_err(idev->dev, "%s: message timeout\n", __func__);
+ i2c_int_disable(idev, ALTR_I2C_ALL_IRQ);
+ i2c_int_clear(idev, ALTR_I2C_ALL_IRQ);
+ complete(&idev->msg_complete);
+
+out:
+ return IRQ_HANDLED;
+}
+
+static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg)
+{
+ u32 int_mask = ALTR_I2C_ISR_RXOF | ALTR_I2C_ISR_ARB | ALTR_I2C_ISR_NACK;
+ u32 addr = (msg->addr << 1) & 0xFF;
+ unsigned long time_left;
+
+ 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);
+
+ if (i2c_m_rd(msg)) {
+ /* Dummy read to ensure RX FIFO is empty */
+ readl(idev->base + ALTR_I2C_RX_DATA);
+ addr |= ALTR_I2C_TFR_CMD_RW_D;
+ }
+
+ writel(ALTR_I2C_TFR_CMD_STA | addr, idev->base + ALTR_I2C_TFR_CMD);
+
+ if (i2c_m_rd(msg)) {
+ /* write the first byte to start the RX */
+ writel(0, idev->base + ALTR_I2C_TFR_CMD);
+ int_mask |= ALTR_I2C_ISER_RXOF_EN | ALTR_I2C_ISER_RXRDY_EN;
+ } else {
+ altr_i2c_fill_tx_fifo(idev);
+ int_mask |= ALTR_I2C_ISR_TXRDY;
+ }
+ i2c_int_enable(idev, int_mask);
+
+ time_left = wait_for_completion_timeout(&idev->msg_complete,
+ ALTR_I2C_XFER_TIMEOUT);
+
+ i2c_int_disable(idev, int_mask);
+
+ if (readl(idev->base + ALTR_I2C_STATUS) & ALTR_I2C_STAT_CORE)
+ dev_err(idev->dev, "%s: Core Status not IDLE...\n", __func__);
+
+ if (time_left == 0) {
+ idev->msg_err = -ETIMEDOUT;
+ dev_err(idev->dev, "%s: Transaction timed out.\n", __func__);
+ altr_i2c_recover(idev);
+ }
+
+ if (unlikely(idev->msg_err) && idev->msg_err != -ENXIO)
+ altr_i2c_init(idev);
+
+ 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;
+ int ret = 0;
+
+ for (i = 0; ret == 0 && i < num; ++i)
+ ret = altr_i2c_xfer_msg(idev, &msgs[i]);
+
+ return ret ? : i;
+}
+
+static u32 altr_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C;
+}
+
+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 device_node *np = pdev->dev.of_node;
+ struct altr_i2c_dev *idev = NULL;
+ struct resource *res;
+ int irq;
+ int ret = 0;
+
+ 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);
+
+ if (of_property_read_u32(np, "fifo-size", &idev->fifo_size))
+ idev->fifo_size = ALTR_I2C_DFLT_FIFO_SZ;
+
+ if (of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate))
+ 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_irq(&pdev->dev, irq, altr_i2c_isr, 0,
+ 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 at linux.intel.com>");
+MODULE_LICENSE("GPL v2");
--
2.7.4
More information about the linux-arm-kernel
mailing list