[PATCH 15/20] serial: stm32: Add wakeup mechanism

From: Bich HEMON
Date: Mon Jun 26 2017 - 08:52:19 EST

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From: Bich Hemon <bich.hemon@xxxxxx>

Add support for wake-up from low power modes. This extends stm32f7.
Introduce new compatible for stm32h7 to manage wake-up capability.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
---
drivers/tty/serial/stm32-usart.c | 90 +++++++++++++++++++++++++++++++++++++++-
drivers/tty/serial/stm32-usart.h | 29 +++++++++++++
2 files changed, 118 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index a62fc95..05d89b0 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -25,6 +25,7 @@
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
+#include <linux/pm_wakeirq.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/spinlock.h>
@@ -374,6 +375,10 @@ static irqreturn_t stm32_interrupt(int irq, void *ptr)
writel_relaxed(USART_ICR_RTOCF,
port->membase + ofs->icr);

+ if ((sr & USART_SR_WUF) && (ofs->icr != UNDEF_REG))
+ writel_relaxed(USART_ICR_WUCF,
+ port->membase + ofs->icr);
+
if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch))
stm32_receive_chars(port, false);

@@ -526,6 +531,7 @@ static int stm32_startup(struct uart_port *port)
{
struct stm32_port *stm32_port = to_stm32_port(port);
struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
const char *name = to_platform_device(port->dev)->name;
u32 val;
int ret;
@@ -536,6 +542,15 @@ static int stm32_startup(struct uart_port *port)
if (ret)
return ret;

+ if (cfg->has_wakeup && stm32_port->wakeirq >= 0) {
+ ret = dev_pm_set_dedicated_wake_irq(port->dev,
+ stm32_port->wakeirq);
+ if (ret) {
+ free_irq(port->irq, port);
+ return ret;
+ }
+ }
+
val = stm32_port->rx_irq | USART_CR1_TE | USART_CR1_RE;
if (stm32_port->fifoen)
val |= USART_CR1_FIFOEN;
@@ -558,6 +573,7 @@ static void stm32_shutdown(struct uart_port *port)
val |= USART_CR1_FIFOEN;
stm32_clr_bits(port, ofs->cr1, val);

+ dev_pm_clear_wake_irq(port->dev);
free_irq(port->irq, port);
}

@@ -758,6 +774,7 @@ static int stm32_init_port(struct stm32_port *stm32port,
port->ops = &stm32_uart_ops;
port->dev = &pdev->dev;
port->irq = platform_get_irq(pdev, 0);
+ stm32port->wakeirq = platform_get_irq(pdev, 1);

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
port->membase = devm_ioremap_resource(&pdev->dev, res);
@@ -819,6 +836,8 @@ static struct stm32_port *stm32_of_get_stm32_port(struct platform_device *pdev)
{ .compatible = "st,stm32-uart", .data = &stm32f4_info},
{ .compatible = "st,stm32f7-usart", .data = &stm32f7_info},
{ .compatible = "st,stm32f7-uart", .data = &stm32f7_info},
+ { .compatible = "st,stm32h7-usart", .data = &stm32h7_info},
+ { .compatible = "st,stm32h7-uart", .data = &stm32h7_info},
{},
};

@@ -964,9 +983,15 @@ static int stm32_serial_probe(struct platform_device *pdev)
if (ret)
return ret;

+ if (stm32port->info->cfg.has_wakeup && stm32port->wakeirq >= 0) {
+ ret = device_init_wakeup(&pdev->dev, true);
+ if (ret)
+ goto err_uninit;
+ }
+
ret = uart_add_one_port(&stm32_usart_driver, &stm32port->port);
if (ret)
- goto err_uninit;
+ goto err_nowup;

ret = stm32_of_dma_rx_probe(stm32port, pdev);
if (ret)
@@ -980,6 +1005,10 @@ static int stm32_serial_probe(struct platform_device *pdev)

return 0;

+err_nowup:
+ if (stm32port->info->cfg.has_wakeup && stm32port->wakeirq >= 0)
+ device_init_wakeup(&pdev->dev, false);
+
err_uninit:
clk_disable_unprepare(stm32port->clk);

@@ -991,6 +1020,7 @@ static int stm32_serial_remove(struct platform_device *pdev)
struct uart_port *port = platform_get_drvdata(pdev);
struct stm32_port *stm32_port = to_stm32_port(port);
struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;

stm32_clr_bits(port, ofs->cr3, USART_CR3_DMAR);

@@ -1016,6 +1046,9 @@ static int stm32_serial_remove(struct platform_device *pdev)
TX_BUF_L, stm32_port->tx_buf,
stm32_port->tx_dma_buf);

+ if (cfg->has_wakeup && stm32_port->wakeirq >= 0)
+ device_init_wakeup(&pdev->dev, false);
+
clk_disable_unprepare(stm32_port->clk);

stm32_serial_debugfs_rm(stm32_port);
@@ -1123,11 +1156,66 @@ static int stm32_console_setup(struct console *co, char *options)
.cons = STM32_SERIAL_CONSOLE,
};

+#ifdef CONFIG_PM_SLEEP
+static void stm32_serial_enable_wakeup(struct uart_port *port, bool enable)
+{
+ struct stm32_port *stm32_port = to_stm32_port(port);
+ struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+ struct stm32_usart_config *cfg = &stm32_port->info->cfg;
+ u32 val;
+
+ if (!cfg->has_wakeup || stm32_port->wakeirq < 0)
+ return;
+
+ if (enable) {
+ stm32_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+ stm32_set_bits(port, ofs->cr1, USART_CR1_UESM);
+ val = readl_relaxed(port->membase + ofs->cr3);
+ val &= ~USART_CR3_WUS_MASK;
+ /* Enable Wake up interrupt from low power on start bit */
+ val |= USART_CR3_WUS_START_BIT | USART_CR3_WUFIE;
+ writel_relaxed(val, port->membase + ofs->cr3);
+ stm32_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));
+ } else {
+ stm32_clr_bits(port, ofs->cr1, USART_CR1_UESM);
+ }
+}
+
+static int stm32_serial_suspend(struct device *dev)
+{
+ struct uart_port *port = dev_get_drvdata(dev);
+
+ uart_suspend_port(&stm32_usart_driver, port);
+
+ if (device_may_wakeup(dev))
+ stm32_serial_enable_wakeup(port, true);
+ else
+ stm32_serial_enable_wakeup(port, false);
+
+ return 0;
+}
+
+static int stm32_serial_resume(struct device *dev)
+{
+ struct uart_port *port = dev_get_drvdata(dev);
+
+ if (device_may_wakeup(dev))
+ stm32_serial_enable_wakeup(port, false);
+
+ return uart_resume_port(&stm32_usart_driver, port);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops stm32_serial_pm_ops = {
+ SET_SYSTEM_SLEEP_PM_OPS(stm32_serial_suspend, stm32_serial_resume)
+};
+
static struct platform_driver stm32_serial_driver = {
.probe = stm32_serial_probe,
.remove = stm32_serial_remove,
.driver = {
.name = DRIVER_NAME,
+ .pm = &stm32_serial_pm_ops,
.of_match_table = of_match_ptr(stm32_match),
},
};
diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h
index 056a837..98dbf38 100644
--- a/drivers/tty/serial/stm32-usart.h
+++ b/drivers/tty/serial/stm32-usart.h
@@ -24,6 +24,7 @@ struct stm32_usart_offsets {
struct stm32_usart_config {
u8 uart_enable_bit; /* USART_CR1_UE */
bool has_7bits_data;
+ bool has_wakeup;
};

struct stm32_usart_info {
@@ -74,6 +75,27 @@ struct stm32_usart_info stm32f7_info = {
}
};

+struct stm32_usart_info stm32h7_info = {
+ .ofs = {
+ .cr1 = 0x00,
+ .cr2 = 0x04,
+ .cr3 = 0x08,
+ .brr = 0x0c,
+ .gtpr = 0x10,
+ .rtor = 0x14,
+ .rqr = 0x18,
+ .isr = 0x1c,
+ .icr = 0x20,
+ .rdr = 0x24,
+ .tdr = 0x28,
+ },
+ .cfg = {
+ .uart_enable_bit = 0,
+ .has_7bits_data = true,
+ .has_wakeup = true,
+ }
+};
+
/* USART_SR (F4) / USART_ISR (F7) */
#define USART_SR_PE BIT(0)
#define USART_SR_FE BIT(1)
@@ -93,6 +115,7 @@ struct stm32_usart_info stm32f7_info = {
#define USART_SR_BUSY BIT(16) /* F7 */
#define USART_SR_CMF BIT(17) /* F7 */
#define USART_SR_SBKF BIT(18) /* F7 */
+#define USART_SR_WUF BIT(20) /* H7 */
#define USART_SR_TEACK BIT(21) /* F7 */
#define USART_SR_ERR_MASK (USART_SR_LBD | USART_SR_ORE | \
USART_SR_FE | USART_SR_PE)
@@ -113,6 +136,7 @@ struct stm32_usart_info stm32f7_info = {
/* USART_CR1 */
#define USART_CR1_SBK BIT(0)
#define USART_CR1_RWU BIT(1) /* F4 */
+#define USART_CR1_UESM BIT(1) /* H7 */
#define USART_CR1_RE BIT(2)
#define USART_CR1_TE BIT(3)
#define USART_CR1_IDLEIE BIT(4)
@@ -176,6 +200,9 @@ struct stm32_usart_info stm32f7_info = {
#define USART_CR3_DEM BIT(14) /* F7 */
#define USART_CR3_DEP BIT(15) /* F7 */
#define USART_CR3_SCARCNT_MASK GENMASK(19, 17) /* F7 */
+#define USART_CR3_WUS_MASK GENMASK(21, 20) /* H7 */
+#define USART_CR3_WUS_START_BIT BIT(21) /* H7 */
+#define USART_CR3_WUFIE BIT(22) /* H7 */

/* USART_GTPR */
#define USART_GTPR_PSC_MASK GENMASK(7, 0)
@@ -204,6 +231,7 @@ struct stm32_usart_info stm32f7_info = {
#define USART_ICR_RTOCF BIT(11) /* F7 */
#define USART_ICR_EOBCF BIT(12) /* F7 */
#define USART_ICR_CMCF BIT(17) /* F7 */
+#define USART_ICR_WUCF BIT(20) /* H7 */

#define STM32_SERIAL_NAME "ttyS"
#define STM32_MAX_PORTS 8
@@ -230,6 +258,7 @@ struct stm32_port {
bool tx_dma_busy; /* dma tx busy */
bool hw_flow_control;
bool fifoen;
+ int wakeirq;
};

static struct stm32_port stm32_ports[STM32_MAX_PORTS];
--
1.9.1

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