[PATCH V4] MXS: Implement DMA support into mxs-i2c
Marek Vasut
marex at denx.de
Thu Aug 23 23:44:31 EDT 2012
This patch implements DMA support into mxs-i2c. DMA transfers are now enabled
via DT. The DMA operation is enabled by default.
Signed-off-by: Marek Vasut <marex at denx.de>
CC: Fabio Estevam <fabio.estevam at freescale.com>
Cc: linux-i2c at vger.kernel.org
CC: Shawn Guo <shawn.guo at linaro.org>
Cc: Wolfram Sang <w.sang at pengutronix.de>
---
Documentation/devicetree/bindings/i2c/i2c-mxs.txt | 2 +
arch/arm/boot/dts/imx28.dtsi | 2 +
drivers/i2c/busses/i2c-mxs.c | 269 +++++++++++++++++++--
3 files changed, 251 insertions(+), 22 deletions(-)
V2: Fixed return value from mxs_i2c_dma_setup_xfer().
Fixed coding style nitpicks
Call mxs_i2c_dma_finish() in failpath only if DMA is active
V3: Align with changes in previous patch
V4: Succumb to nonsense for the greater good ... like working EEPROMs
Add "use_pioqueue" module parameter
diff --git a/Documentation/devicetree/bindings/i2c/i2c-mxs.txt b/Documentation/devicetree/bindings/i2c/i2c-mxs.txt
index 30ac3a0..7a3fe9e 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-mxs.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-mxs.txt
@@ -6,6 +6,7 @@ Required properties:
- interrupts: Should contain ERROR and DMA interrupts
- clock-frequency: Desired I2C bus clock frequency in Hz.
Only 100000Hz and 400000Hz modes are supported.
+- fsl,i2c-dma-channel: APBX DMA channel for the I2C
Examples:
@@ -16,4 +17,5 @@ i2c0: i2c at 80058000 {
reg = <0x80058000 2000>;
interrupts = <111 68>;
clock-frequency = <100000>;
+ fsl,i2c-dma-channel = <6>;
};
diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
index 3fa6d19..ba8227e 100644
--- a/arch/arm/boot/dts/imx28.dtsi
+++ b/arch/arm/boot/dts/imx28.dtsi
@@ -661,6 +661,7 @@
reg = <0x80058000 0x2000>;
interrupts = <111 68>;
clock-frequency = <100000>;
+ fsl,i2c-dma-channel = <6>;
status = "disabled";
};
@@ -671,6 +672,7 @@
reg = <0x8005a000 0x2000>;
interrupts = <110 69>;
clock-frequency = <100000>;
+ fsl,i2c-dma-channel = <7>;
status = "disabled";
};
diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
index 088c5c1..83c3a7e 100644
--- a/drivers/i2c/busses/i2c-mxs.c
+++ b/drivers/i2c/busses/i2c-mxs.c
@@ -7,8 +7,6 @@
*
* Copyright (C) 2009-2010 Freescale Semiconductor, Inc. All Rights Reserved.
*
- * TODO: add dma-support if platform-support for it is available
- *
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
@@ -31,9 +29,16 @@
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_i2c.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/fsl/mxs-dma.h>
#define DRIVER_NAME "mxs-i2c"
+static bool use_pioqueue;
+module_param(use_pioqueue, bool, 0);
+MODULE_PARM_DESC(use_pioqueue, "Use PIOQUEUE mode for transfer instead of DMA");
+
#define MXS_I2C_CTRL0 (0x00)
#define MXS_I2C_CTRL0_SET (0x04)
@@ -146,6 +151,16 @@ struct mxs_i2c_dev {
u32 cmd_err;
struct i2c_adapter adapter;
const struct mxs_i2c_speed_config *speed;
+
+ /* DMA support components */
+ bool dma_mode;
+ int dma_channel;
+ struct dma_chan *dmach;
+ struct mxs_dma_data dma_data;
+ uint32_t pio_data[2];
+ uint32_t addr_data;
+ struct scatterlist sg_io[2];
+ bool dma_read;
};
static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
@@ -157,7 +172,11 @@ static void mxs_i2c_reset(struct mxs_i2c_dev *i2c)
writel(i2c->speed->timing2, i2c->regs + MXS_I2C_TIMING2);
writel(MXS_I2C_IRQ_MASK << 8, i2c->regs + MXS_I2C_CTRL1_SET);
- writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
+ if (i2c->dma_mode)
+ writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
+ i2c->regs + MXS_I2C_QUEUECTRL_CLR);
+ else
+ writel(MXS_I2C_QUEUECTRL_PIO_QUEUE_MODE,
i2c->regs + MXS_I2C_QUEUECTRL_SET);
}
@@ -248,6 +267,150 @@ static int mxs_i2c_finish_read(struct mxs_i2c_dev *i2c, u8 *buf, int len)
return 0;
}
+static void mxs_i2c_dma_finish(struct mxs_i2c_dev *i2c)
+{
+ if (i2c->dma_read) {
+ dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
+ dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
+ } else {
+ dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
+ }
+}
+
+static void mxs_i2c_dma_irq_callback(void *param)
+{
+ struct mxs_i2c_dev *i2c = param;
+
+ complete(&i2c->cmd_complete);
+ mxs_i2c_dma_finish(i2c);
+}
+
+static int mxs_i2c_dma_setup_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msg, uint32_t flags)
+{
+ struct dma_async_tx_descriptor *desc;
+ struct mxs_i2c_dev *i2c = i2c_get_adapdata(adap);
+
+ if (msg->flags & I2C_M_RD) {
+ i2c->dma_read = 1;
+ i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_READ;
+
+ /*
+ * SELECT command.
+ */
+
+ /* Queue the PIO register write transfer. */
+ i2c->pio_data[0] = MXS_CMD_I2C_SELECT;
+ desc = dmaengine_prep_slave_sg(i2c->dmach,
+ (struct scatterlist *)&i2c->pio_data[0],
+ 1, DMA_TRANS_NONE, 0);
+ if (!desc) {
+ dev_err(i2c->dev,
+ "Failed to get PIO reg. write descriptor.\n");
+ goto select_init_pio_fail;
+ }
+
+ /* Queue the DMA data transfer. */
+ sg_init_one(&i2c->sg_io[0], &i2c->addr_data, 1);
+ dma_map_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
+ desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[0], 1,
+ DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc) {
+ dev_err(i2c->dev,
+ "Failed to get DMA data write descriptor.\n");
+ goto select_init_dma_fail;
+ }
+
+ /*
+ * READ command.
+ */
+
+ /* Queue the PIO register write transfer. */
+ i2c->pio_data[1] = flags | MXS_CMD_I2C_READ |
+ MXS_I2C_CTRL0_XFER_COUNT(msg->len);
+ desc = dmaengine_prep_slave_sg(i2c->dmach,
+ (struct scatterlist *)&i2c->pio_data[1],
+ 1, DMA_TRANS_NONE, DMA_PREP_INTERRUPT);
+ if (!desc) {
+ dev_err(i2c->dev,
+ "Failed to get PIO reg. write descriptor.\n");
+ goto select_init_dma_fail;
+ }
+
+ /* Queue the DMA data transfer. */
+ sg_init_one(&i2c->sg_io[1], msg->buf, msg->len);
+ dma_map_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
+ desc = dmaengine_prep_slave_sg(i2c->dmach, &i2c->sg_io[1], 1,
+ DMA_DEV_TO_MEM,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc) {
+ dev_err(i2c->dev,
+ "Failed to get DMA data write descriptor.\n");
+ goto read_init_dma_fail;
+ }
+ } else {
+ i2c->dma_read = 0;
+ i2c->addr_data = (msg->addr << 1) | I2C_SMBUS_WRITE;
+
+ /*
+ * WRITE command.
+ */
+
+ /* Queue the PIO register write transfer. */
+ i2c->pio_data[0] = flags | MXS_CMD_I2C_WRITE |
+ MXS_I2C_CTRL0_XFER_COUNT(msg->len + 1);
+ desc = dmaengine_prep_slave_sg(i2c->dmach,
+ (struct scatterlist *)&i2c->pio_data[0],
+ 1, DMA_TRANS_NONE, 0);
+ if (!desc) {
+ dev_err(i2c->dev,
+ "Failed to get PIO reg. write descriptor.\n");
+ goto write_init_pio_fail;
+ }
+
+ /* Queue the DMA data transfer. */
+ sg_init_table(i2c->sg_io, 2);
+ sg_set_buf(&i2c->sg_io[0], &i2c->addr_data, 1);
+ sg_set_buf(&i2c->sg_io[1], msg->buf, msg->len);
+ dma_map_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
+ desc = dmaengine_prep_slave_sg(i2c->dmach, i2c->sg_io, 2,
+ DMA_MEM_TO_DEV,
+ DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+ if (!desc) {
+ dev_err(i2c->dev,
+ "Failed to get DMA data write descriptor.\n");
+ goto write_init_dma_fail;
+ }
+ }
+
+ /*
+ * The last descriptor must have this callback,
+ * to finish the DMA transaction.
+ */
+ desc->callback = mxs_i2c_dma_irq_callback;
+ desc->callback_param = i2c;
+
+ /* Start the transfer. */
+ dmaengine_submit(desc);
+ dma_async_issue_pending(i2c->dmach);
+ return 0;
+
+/* Read failpath. */
+read_init_dma_fail:
+ dma_unmap_sg(i2c->dev, &i2c->sg_io[1], 1, DMA_FROM_DEVICE);
+select_init_dma_fail:
+ dma_unmap_sg(i2c->dev, &i2c->sg_io[0], 1, DMA_TO_DEVICE);
+select_init_pio_fail:
+ return -EINVAL;
+
+/* Write failpath. */
+write_init_dma_fail:
+ dma_unmap_sg(i2c->dev, i2c->sg_io, 2, DMA_TO_DEVICE);
+write_init_pio_fail:
+ return -EINVAL;
+}
+
/*
* Low level master read/write transaction.
*/
@@ -258,6 +421,8 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
int ret;
int flags;
+ flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
+
dev_dbg(i2c->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
msg->addr, msg->len, msg->flags, stop);
@@ -267,23 +432,29 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
init_completion(&i2c->cmd_complete);
i2c->cmd_err = 0;
- flags = stop ? MXS_I2C_CTRL0_POST_SEND_STOP : 0;
-
- if (msg->flags & I2C_M_RD)
- mxs_i2c_pioq_setup_read(i2c, msg->addr, msg->len, flags);
- else
- mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf, msg->len,
- flags);
+ if (i2c->dma_mode) {
+ ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
+ if (ret)
+ return ret;
+ } else {
+ if (msg->flags & I2C_M_RD) {
+ mxs_i2c_pioq_setup_read(i2c, msg->addr,
+ msg->len, flags);
+ } else {
+ mxs_i2c_pioq_setup_write(i2c, msg->addr, msg->buf,
+ msg->len, flags);
+ }
- writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
+ writel(MXS_I2C_QUEUECTRL_QUEUE_RUN,
i2c->regs + MXS_I2C_QUEUECTRL_SET);
+ }
ret = wait_for_completion_timeout(&i2c->cmd_complete,
msecs_to_jiffies(1000));
if (ret == 0)
goto timeout;
- if ((!i2c->cmd_err) && (msg->flags & I2C_M_RD)) {
+ if (!i2c->dma_mode && !i2c->cmd_err && (msg->flags & I2C_M_RD)) {
ret = mxs_i2c_finish_read(i2c, msg->buf, msg->len);
if (ret)
goto timeout;
@@ -301,6 +472,8 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
timeout:
dev_dbg(i2c->dev, "Timeout!\n");
+ if (i2c->dma_mode)
+ mxs_i2c_dma_finish(i2c);
mxs_i2c_reset(i2c);
return -ETIMEDOUT;
}
@@ -342,11 +515,13 @@ static irqreturn_t mxs_i2c_isr(int this_irq, void *dev_id)
/* MXS_I2C_CTRL1_OVERSIZE_XFER_TERM_IRQ is only for slaves */
i2c->cmd_err = -EIO;
- is_last_cmd = (readl(i2c->regs + MXS_I2C_QUEUESTAT) &
- MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK) == 0;
+ if (!i2c->dma_mode) {
+ is_last_cmd = (readl(i2c->regs + MXS_I2C_QUEUESTAT) &
+ MXS_I2C_QUEUESTAT_WRITE_QUEUE_CNT_MASK) == 0;
- if (is_last_cmd || i2c->cmd_err)
- complete(&i2c->cmd_complete);
+ if (is_last_cmd || i2c->cmd_err)
+ complete(&i2c->cmd_complete);
+ }
writel(stat, i2c->regs + MXS_I2C_CTRL1_CLR);
@@ -358,6 +533,21 @@ static const struct i2c_algorithm mxs_i2c_algo = {
.functionality = mxs_i2c_func,
};
+static bool mxs_i2c_dma_filter(struct dma_chan *chan, void *param)
+{
+ struct mxs_i2c_dev *i2c = param;
+
+ if (!mxs_dma_is_apbx(chan))
+ return false;
+
+ if (chan->chan_id != i2c->dma_channel)
+ return false;
+
+ chan->private = &i2c->dma_data;
+
+ return true;
+}
+
static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
{
uint32_t speed;
@@ -368,6 +558,26 @@ static int mxs_i2c_get_ofdata(struct mxs_i2c_dev *i2c)
if (!node)
return -EINVAL;
+ /*
+ * The MXS I2C DMA mode is prefered and enabled by default.
+ * The PIO mode is still supported, but should be used only
+ * for debuging purposes etc.
+ */
+ i2c->dma_mode = !use_pioqueue;
+ if (!i2c->dma_mode)
+ dev_info(dev, "Using PIOQUEUE mode for I2C transfers!\n");
+
+ /*
+ * TODO: This is a temporary solution and should be changed
+ * to use generic DMA binding later when the helpers get in.
+ */
+ ret = of_property_read_u32(node, "fsl,i2c-dma-channel",
+ &i2c->dma_channel);
+ if (ret) {
+ dev_warn(dev, "Failed to get DMA channel, using PIOQUEUE!\n");
+ i2c->dma_mode = 0;
+ }
+
i2c->speed = &mxs_i2c_95kHz_config;
ret = of_property_read_u32(node, "clock-frequency", &speed);
if (ret)
@@ -388,7 +598,8 @@ static int __devinit mxs_i2c_probe(struct platform_device *pdev)
struct pinctrl *pinctrl;
struct resource *res;
resource_size_t res_size;
- int err, irq;
+ int err, irq, dmairq;
+ dma_cap_mask_t mask;
pinctrl = devm_pinctrl_get_select_default(dev);
if (IS_ERR(pinctrl))
@@ -399,7 +610,10 @@ static int __devinit mxs_i2c_probe(struct platform_device *pdev)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- if (!res)
+ irq = platform_get_irq(pdev, 0);
+ dmairq = platform_get_irq(pdev, 1);
+
+ if (!res || irq < 0 || dmairq < 0)
return -ENOENT;
res_size = resource_size(res);
@@ -410,10 +624,6 @@ static int __devinit mxs_i2c_probe(struct platform_device *pdev)
if (!i2c->regs)
return -EBUSY;
- irq = platform_get_irq(pdev, 0);
- if (irq < 0)
- return irq;
-
err = devm_request_irq(dev, irq, mxs_i2c_isr, 0, dev_name(dev), i2c);
if (err)
return err;
@@ -424,6 +634,18 @@ static int __devinit mxs_i2c_probe(struct platform_device *pdev)
if (err)
return err;
+ /* Setup the DMA */
+ if (i2c->dma_mode) {
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
+ i2c->dma_data.chan_irq = dmairq;
+ i2c->dmach = dma_request_channel(mask, mxs_i2c_dma_filter, i2c);
+ if (!i2c->dmach) {
+ dev_err(dev, "Failed to request dma\n");
+ return -ENODEV;
+ }
+ }
+
platform_set_drvdata(pdev, i2c);
/* Do reset to enforce correct startup after pinmuxing */
@@ -459,6 +681,9 @@ static int __devexit mxs_i2c_remove(struct platform_device *pdev)
if (ret)
return -EBUSY;
+ if (i2c->dmach)
+ dma_release_channel(i2c->dmach);
+
writel(MXS_I2C_CTRL0_SFTRST, i2c->regs + MXS_I2C_CTRL0_SET);
platform_set_drvdata(pdev, NULL);
--
1.7.10.4
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