[PATCH v2 5/6] i2c: i2c-stm32f7: Add DMA support

Pierre-Yves MORDRET
2018-03-21T16:48:59Z

This patch adds DMA support for i2c-stm32f7 driver

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
---
Version history:
v1:
* Initial
v2:
* fix kbuild test robot issue (format)
---

fixup! i2c: i2c-stm32f7: Add DMA support
---
drivers/i2c/busses/Makefile | 3 +-
drivers/i2c/busses/i2c-stm32f7.c | 214 +++++++++++++++++++++++++++++++++++----
2 files changed, 196 insertions(+), 21 deletions(-)

diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 2ce8576..8dbfaf0 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -95,7 +95,8 @@ obj-$(CONFIG_I2C_SIRF) += i2c-sirf.o
obj-$(CONFIG_I2C_SPRD) += i2c-sprd.o
obj-$(CONFIG_I2C_ST) += i2c-st.o
obj-$(CONFIG_I2C_STM32F4) += i2c-stm32f4.o
-obj-$(CONFIG_I2C_STM32F7) += i2c-stm32f7.o
+i2c-stm32f7-drv-objs := i2c-stm32f7.o i2c-stm32.o
+obj-$(CONFIG_I2C_STM32F7) += i2c-stm32f7-drv.o
obj-$(CONFIG_I2C_STU300) += i2c-stu300.o
obj-$(CONFIG_I2C_SUN6I_P2WI) += i2c-sun6i-p2wi.o
obj-$(CONFIG_I2C_TEGRA) += i2c-tegra.o
diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 0b81b5d..91f73e0 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -47,6 +47,8 @@
/* STM32F7 I2C control 1 */
#define STM32F7_I2C_CR1_PECEN BIT(23)
#define STM32F7_I2C_CR1_SBC BIT(16)
+#define STM32F7_I2C_CR1_RXDMAEN BIT(15)
+#define STM32F7_I2C_CR1_TXDMAEN BIT(14)
#define STM32F7_I2C_CR1_ANFOFF BIT(12)
#define STM32F7_I2C_CR1_ERRIE BIT(7)
#define STM32F7_I2C_CR1_TCIE BIT(6)
@@ -142,6 +144,7 @@
#define STM32F7_I2C_TIMINGR_SCLL(n) ((n) & 0xff)

#define STM32F7_I2C_MAX_LEN 0xff
+#define STM32F7_I2C_DMA_LEN_MIN 0x1
#define STM32F7_I2C_MAX_SLAVE 0x2

#define STM32F7_I2C_DNF_DEFAULT 0
@@ -270,6 +273,8 @@ struct stm32f7_i2c_msg {
* @slave_dir: transfer direction for the current slave device
* @master_mode: boolean to know in which mode the I2C is running (master or
* slave)
+ * @dma: dma data
+ * @use_dma: boolean to know if dma is used in the current transfer
*/
struct stm32f7_i2c_dev {
struct i2c_adapter adap;
@@ -288,6 +293,8 @@ struct stm32f7_i2c_dev {
struct i2c_client *slave_running;
u32 slave_dir;
bool master_mode;
+ struct stm32_i2c_dma *dma;
+ bool use_dma;
};

/**
@@ -599,6 +606,25 @@ static int stm32f7_i2c_setup_timing(struct stm32f7_i2c_dev *i2c_dev,
return 0;
}

+static void stm32f7_i2c_disable_dma_req(struct stm32f7_i2c_dev *i2c_dev)
+{
+ void __iomem *base = i2c_dev->base;
+ u32 mask = STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN;
+
+ stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR1, mask);
+}
+
+static void stm32f7_i2c_dma_callback(void *arg)
+{
+ struct stm32f7_i2c_dev *i2c_dev = (struct stm32f7_i2c_dev *)arg;
+ struct stm32_i2c_dma *dma = i2c_dev->dma;
+ struct device *dev = dma->chan_using->device->dev;
+
+ stm32f7_i2c_disable_dma_req(i2c_dev);
+ dma_unmap_single(dev, dma->dma_buf, dma->dma_len, dma->dma_data_dir);
+ complete(&dma->dma_complete);
+}
+
static void stm32f7_i2c_hw_config(struct stm32f7_i2c_dev *i2c_dev)
{
struct stm32f7_i2c_timings *t = &i2c_dev->timing;
@@ -653,6 +679,9 @@ static void stm32f7_i2c_reload(struct stm32f7_i2c_dev *i2c_dev)
struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
u32 cr2;

+ if (i2c_dev->use_dma)
+ f7_msg->count -= STM32F7_I2C_MAX_LEN;
+
cr2 = readl_relaxed(i2c_dev->base + STM32F7_I2C_CR2);

cr2 &= ~STM32F7_I2C_CR2_NBYTES_MASK;
@@ -712,6 +741,7 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
void __iomem *base = i2c_dev->base;
u32 cr1, cr2;
+ int ret;

f7_msg->addr = msg->addr;
f7_msg->buf = msg->buf;
@@ -753,14 +783,35 @@ static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
cr1 |= STM32F7_I2C_CR1_ERRIE | STM32F7_I2C_CR1_TCIE |
STM32F7_I2C_CR1_STOPIE | STM32F7_I2C_CR1_NACKIE;

- /* Clear TX/RX interrupt */
- cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
+ /* Clear DMA req and TX/RX interrupt */
+ cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE |
+ STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN);
+
+ /* Configure DMA or enable RX/TX interrupt */
+ i2c_dev->use_dma = false;
+ if (i2c_dev->dma && f7_msg->count >= STM32F7_I2C_DMA_LEN_MIN) {
+ ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
+ msg->flags & I2C_M_RD,
+ f7_msg->count, f7_msg->buf,
+ stm32f7_i2c_dma_callback,
+ i2c_dev);
+ if (!ret)
+ i2c_dev->use_dma = true;
+ else
+ dev_warn(i2c_dev->dev, "can't use DMA\n");
+ }

- /* Enable RX/TX interrupt according to msg direction */
- if (msg->flags & I2C_M_RD)
- cr1 |= STM32F7_I2C_CR1_RXIE;
- else
- cr1 |= STM32F7_I2C_CR1_TXIE;
+ if (!i2c_dev->use_dma) {
+ if (msg->flags & I2C_M_RD)
+ cr1 |= STM32F7_I2C_CR1_RXIE;
+ else
+ cr1 |= STM32F7_I2C_CR1_TXIE;
+ } else {
+ if (msg->flags & I2C_M_RD)
+ cr1 |= STM32F7_I2C_CR1_RXDMAEN;
+ else
+ cr1 |= STM32F7_I2C_CR1_TXDMAEN;
+ }

/* Configure Start/Repeated Start */
cr2 |= STM32F7_I2C_CR2_START;
@@ -780,7 +831,7 @@ static int stm32f7_i2c_smbus_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
struct device *dev = i2c_dev->dev;
void __iomem *base = i2c_dev->base;
u32 cr1, cr2;
- int i;
+ int i, ret;

f7_msg->result = 0;
reinit_completion(&i2c_dev->complete);
@@ -895,14 +946,35 @@ static int stm32f7_i2c_smbus_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
cr1 |= STM32F7_I2C_CR1_ERRIE | STM32F7_I2C_CR1_TCIE |
STM32F7_I2C_CR1_STOPIE | STM32F7_I2C_CR1_NACKIE;

- /* Clear TX/RX interrupt */
- cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
+ /* Clear DMA req and TX/RX interrupt */
+ cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE |
+ STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN);
+
+ /* Configure DMA or enable RX/TX interrupt */
+ i2c_dev->use_dma = false;
+ if (i2c_dev->dma && f7_msg->count >= STM32F7_I2C_DMA_LEN_MIN) {
+ ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
+ cr2 & STM32F7_I2C_CR2_RD_WRN,
+ f7_msg->count, f7_msg->buf,
+ stm32f7_i2c_dma_callback,
+ i2c_dev);
+ if (!ret)
+ i2c_dev->use_dma = true;
+ else
+ dev_warn(i2c_dev->dev, "can't use DMA\n");
+ }

- /* Enable RX/TX interrupt according to msg direction */
- if (cr2 & STM32F7_I2C_CR2_RD_WRN)
- cr1 |= STM32F7_I2C_CR1_RXIE;
- else
- cr1 |= STM32F7_I2C_CR1_TXIE;
+ if (!i2c_dev->use_dma) {
+ if (cr2 & STM32F7_I2C_CR2_RD_WRN)
+ cr1 |= STM32F7_I2C_CR1_RXIE;
+ else
+ cr1 |= STM32F7_I2C_CR1_TXIE;
+ } else {
+ if (cr2 & STM32F7_I2C_CR2_RD_WRN)
+ cr1 |= STM32F7_I2C_CR1_RXDMAEN;
+ else
+ cr1 |= STM32F7_I2C_CR1_TXDMAEN;
+ }

/* Set Start bit */
cr2 |= STM32F7_I2C_CR2_START;
@@ -921,6 +993,7 @@ static void stm32f7_i2c_smbus_rep_start(struct stm32f7_i2c_dev *i2c_dev)
struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
void __iomem *base = i2c_dev->base;
u32 cr1, cr2;
+ int ret;

cr2 = readl_relaxed(base + STM32F7_I2C_CR2);
cr1 = readl_relaxed(base + STM32F7_I2C_CR1);
@@ -960,6 +1033,35 @@ static void stm32f7_i2c_smbus_rep_start(struct stm32f7_i2c_dev *i2c_dev)
cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE);
cr1 |= STM32F7_I2C_CR1_RXIE;

+ /*
+ * Configure DMA or enable RX/TX interrupt:
+ * For I2C_SMBUS_BLOCK_DATA and I2C_SMBUS_BLOCK_PROC_CALL we don't use
+ * dma as we don't know in advance how many data will be received
+ */
+ cr1 &= ~(STM32F7_I2C_CR1_RXIE | STM32F7_I2C_CR1_TXIE |
+ STM32F7_I2C_CR1_RXDMAEN | STM32F7_I2C_CR1_TXDMAEN);
+
+ i2c_dev->use_dma = false;
+ if (i2c_dev->dma && f7_msg->count >= STM32F7_I2C_DMA_LEN_MIN &&
+ f7_msg->size != I2C_SMBUS_BLOCK_DATA &&
+ f7_msg->size != I2C_SMBUS_BLOCK_PROC_CALL) {
+ ret = stm32_i2c_prep_dma_xfer(i2c_dev->dev, i2c_dev->dma,
+ cr2 & STM32F7_I2C_CR2_RD_WRN,
+ f7_msg->count, f7_msg->buf,
+ stm32f7_i2c_dma_callback,
+ i2c_dev);
+
+ if (!ret)
+ i2c_dev->use_dma = true;
+ else
+ dev_warn(i2c_dev->dev, "can't use DMA\n");
+ }
+
+ if (!i2c_dev->use_dma)
+ cr1 |= STM32F7_I2C_CR1_RXIE;
+ else
+ cr1 |= STM32F7_I2C_CR1_RXDMAEN;
+
/* Configure Repeated Start */
cr2 |= STM32F7_I2C_CR2_START;

@@ -1248,7 +1350,7 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
void __iomem *base = i2c_dev->base;
u32 status, mask;
- int ret;
+ int ret = IRQ_HANDLED;

/* Check if the interrupt if for a slave device */
if (!i2c_dev->master_mode) {
@@ -1285,8 +1387,12 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
/* Clear STOP flag */
writel_relaxed(STM32F7_I2C_ICR_STOPCF, base + STM32F7_I2C_ICR);

- i2c_dev->master_mode = false;
- complete(&i2c_dev->complete);
+ if (i2c_dev->use_dma) {
+ ret = IRQ_WAKE_THREAD;
+ } else {
+ i2c_dev->master_mode = false;
+ complete(&i2c_dev->complete);
+ }
}

/* Transfer complete */
@@ -1294,6 +1400,8 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
if (f7_msg->stop) {
mask = STM32F7_I2C_CR2_STOP;
stm32f7_i2c_set_bits(base + STM32F7_I2C_CR2, mask);
+ } else if (i2c_dev->use_dma) {
+ ret = IRQ_WAKE_THREAD;
} else if (f7_msg->smbus) {
stm32f7_i2c_smbus_rep_start(i2c_dev);
} else {
@@ -1310,6 +1418,44 @@ static irqreturn_t stm32f7_i2c_isr_event(int irq, void *data)
stm32f7_i2c_reload(i2c_dev);
}

+ return ret;
+}
+
+static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
+{
+ struct stm32f7_i2c_dev *i2c_dev = data;
+ struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ struct stm32_i2c_dma *dma = i2c_dev->dma;
+ u32 status;
+ int ret;
+
+ /*
+ * Wait for dma transfer completion before sending next message or
+ * notity the end of xfer to the client
+ */
+ ret = wait_for_completion_timeout(&i2c_dev->dma->dma_complete, HZ);
+ if (!ret) {
+ dev_dbg(i2c_dev->dev, "<%s>: Timed out\n", __func__);
+ stm32f7_i2c_disable_dma_req(i2c_dev);
+ dmaengine_terminate_all(dma->chan_using);
+ f7_msg->result = -ETIMEDOUT;
+ }
+
+ status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
+
+ if (status & STM32F7_I2C_ISR_TC) {
+ if (f7_msg->smbus) {
+ stm32f7_i2c_smbus_rep_start(i2c_dev);
+ } else {
+ i2c_dev->msg_id++;
+ i2c_dev->msg++;
+ stm32f7_i2c_xfer_msg(i2c_dev, i2c_dev->msg);
+ }
+ } else {
+ i2c_dev->master_mode = false;
+ complete(&i2c_dev->complete);
+ }
+
return IRQ_HANDLED;
}

@@ -1319,6 +1465,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
void __iomem *base = i2c_dev->base;
struct device *dev = i2c_dev->dev;
+ struct stm32_i2c_dma *dma = i2c_dev->dma;
u32 mask, status;

status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
@@ -1350,6 +1497,12 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
mask = STM32F7_I2C_ALL_IRQ_MASK;
stm32f7_i2c_disable_irq(i2c_dev, mask);

+ /* Disable dma */
+ if (i2c_dev->use_dma) {
+ stm32f7_i2c_disable_dma_req(i2c_dev);
+ dmaengine_terminate_all(dma->chan_using);
+ }
+
i2c_dev->master_mode = false;
complete(&i2c_dev->complete);

@@ -1361,6 +1514,7 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
{
struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ struct stm32_i2c_dma *dma = i2c_dev->dma;
unsigned long time_left;
int ret;

@@ -1388,6 +1542,8 @@ static int stm32f7_i2c_xfer(struct i2c_adapter *i2c_adap,
if (!time_left) {
dev_dbg(i2c_dev->dev, "Access to slave 0x%x timed out\n",
i2c_dev->msg->addr);
+ if (i2c_dev->use_dma)
+ dmaengine_terminate_all(dma->chan_using);
ret = -ETIMEDOUT;
}

@@ -1404,6 +1560,7 @@ static int stm32f7_i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
{
struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(adapter);
struct stm32f7_i2c_msg *f7_msg = &i2c_dev->f7_msg;
+ struct stm32_i2c_dma *dma = i2c_dev->dma;
struct device *dev = i2c_dev->dev;
unsigned long timeout;
int i, ret;
@@ -1435,6 +1592,8 @@ static int stm32f7_i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,

if (!timeout) {
dev_dbg(dev, "Access to slave 0x%x timed out\n", f7_msg->addr);
+ if (i2c_dev->use_dma)
+ dmaengine_terminate_all(dma->chan_using);
ret = -ETIMEDOUT;
goto clk_free;
}
@@ -1608,6 +1767,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
u32 irq_error, irq_event, clk_rate, rise_time, fall_time;
struct i2c_adapter *adap;
struct reset_control *rst;
+ dma_addr_t phy_addr;
int ret;

i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL);
@@ -1618,6 +1778,7 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
i2c_dev->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(i2c_dev->base))
return PTR_ERR(i2c_dev->base);
+ phy_addr = (dma_addr_t)res->start;

irq_event = irq_of_parse_and_map(np, 0);
if (!irq_event) {
@@ -1664,8 +1825,11 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)

i2c_dev->dev = &pdev->dev;

- ret = devm_request_irq(&pdev->dev, irq_event, stm32f7_i2c_isr_event, 0,
- pdev->name, i2c_dev);
+ ret = devm_request_threaded_irq(&pdev->dev, irq_event,
+ stm32f7_i2c_isr_event,
+ stm32f7_i2c_isr_event_thread,
+ IRQF_ONESHOT,
+ pdev->name, i2c_dev);
if (ret) {
dev_err(&pdev->dev, "Failed to request irq event %i\n",
irq_event);
@@ -1717,6 +1881,11 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)

init_completion(&i2c_dev->complete);

+ /* Init DMA config if supported */
+ i2c_dev->dma = stm32_i2c_dma_request(i2c_dev->dev, phy_addr,
+ STM32F7_I2C_TXDR,
+ STM32F7_I2C_RXDR);
+
ret = i2c_add_adapter(adap);
if (ret)
goto clk_free;
@@ -1739,6 +1908,11 @@ static int stm32f7_i2c_remove(struct platform_device *pdev)
{
struct stm32f7_i2c_dev *i2c_dev = platform_get_drvdata(pdev);

+ if (i2c_dev->dma) {
+ stm32_i2c_dma_free(i2c_dev->dma);
+ i2c_dev->dma = NULL;
+ }
+
i2c_del_adapter(&i2c_dev->adap);

clk_unprepare(i2c_dev->clk);
--
2.7.4