[PATCH 3.11 033/144] can: flexcan: fix transition from and to low power mode in chip_{en,dis}able

From: Luis Henriques
Date: Tue Apr 01 2014 - 08:13:05 EST


3.11.10.7 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>

commit 9b00b300e7bce032c467c36ca47fe2a776887fc2 upstream.

In flexcan_chip_enable() and flexcan_chip_disable() fixed delays are used.
Experiments have shown that the transition from and to low power mode may take
several microseconds.

This patch adds a while loop which polls the Low Power Mode ACK bit (LPM_ACK)
that indicates a successfull mode change. If the function runs into a timeout a
error value is returned.

Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
drivers/net/can/flexcan.c | 50 +++++++++++++++++++++++++++++++++++------------
1 file changed, 38 insertions(+), 12 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 0bd9e2f..c9ea959 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -144,6 +144,8 @@

#define FLEXCAN_MB_CODE_MASK (0xf0ffffff)

+#define FLEXCAN_TIMEOUT_US (50)
+
/*
* FLEXCAN hardware feature flags
*
@@ -266,26 +268,42 @@ static inline int flexcan_has_and_handle_berr(const struct flexcan_priv *priv,
(reg_esr & FLEXCAN_ESR_ERR_BUS);
}

-static inline void flexcan_chip_enable(struct flexcan_priv *priv)
+static int flexcan_chip_enable(struct flexcan_priv *priv)
{
struct flexcan_regs __iomem *regs = priv->base;
+ unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
u32 reg;

reg = flexcan_read(&regs->mcr);
reg &= ~FLEXCAN_MCR_MDIS;
flexcan_write(reg, &regs->mcr);

- udelay(10);
+ while (timeout-- && (flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
+ usleep_range(10, 20);
+
+ if (flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK)
+ return -ETIMEDOUT;
+
+ return 0;
}

-static inline void flexcan_chip_disable(struct flexcan_priv *priv)
+static int flexcan_chip_disable(struct flexcan_priv *priv)
{
struct flexcan_regs __iomem *regs = priv->base;
+ unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
u32 reg;

reg = flexcan_read(&regs->mcr);
reg |= FLEXCAN_MCR_MDIS;
flexcan_write(reg, &regs->mcr);
+
+ while (timeout-- && !(flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
+ usleep_range(10, 20);
+
+ if (!(flexcan_read(&regs->mcr) & FLEXCAN_MCR_LPM_ACK))
+ return -ETIMEDOUT;
+
+ return 0;
}

static int flexcan_get_berr_counter(const struct net_device *dev,
@@ -706,7 +724,9 @@ static int flexcan_chip_start(struct net_device *dev)
u32 reg_mcr, reg_ctrl;

/* enable module */
- flexcan_chip_enable(priv);
+ err = flexcan_chip_enable(priv);
+ if (err)
+ return err;

/* soft reset */
flexcan_write(FLEXCAN_MCR_SOFTRST, &regs->mcr);
@@ -946,12 +966,16 @@ static int register_flexcandev(struct net_device *dev)
goto out_disable_ipg;

/* select "bus clock", chip must be disabled */
- flexcan_chip_disable(priv);
+ err = flexcan_chip_disable(priv);
+ if (err)
+ goto out_disable_per;
reg = flexcan_read(&regs->ctrl);
reg |= FLEXCAN_CTRL_CLK_SRC;
flexcan_write(reg, &regs->ctrl);

- flexcan_chip_enable(priv);
+ err = flexcan_chip_enable(priv);
+ if (err)
+ goto out_chip_disable;

/* set freeze, halt and activate FIFO, restrict register access */
reg = flexcan_read(&regs->mcr);
@@ -968,14 +992,15 @@ static int register_flexcandev(struct net_device *dev)
if (!(reg & FLEXCAN_MCR_FEN)) {
netdev_err(dev, "Could not enable RX FIFO, unsupported core\n");
err = -ENODEV;
- goto out_disable_per;
+ goto out_chip_disable;
}

err = register_candev(dev);

- out_disable_per:
/* disable core and turn off clocks */
+ out_chip_disable:
flexcan_chip_disable(priv);
+ out_disable_per:
clk_disable_unprepare(priv->clk_per);
out_disable_ipg:
clk_disable_unprepare(priv->clk_ipg);
@@ -1147,8 +1172,11 @@ static int flexcan_suspend(struct device *device)
{
struct net_device *dev = dev_get_drvdata(device);
struct flexcan_priv *priv = netdev_priv(dev);
+ int err;

- flexcan_chip_disable(priv);
+ err = flexcan_chip_disable(priv);
+ if (err)
+ return err;

if (netif_running(dev)) {
netif_stop_queue(dev);
@@ -1169,9 +1197,7 @@ static int flexcan_resume(struct device *device)
netif_device_attach(dev);
netif_start_queue(dev);
}
- flexcan_chip_enable(priv);
-
- return 0;
+ return flexcan_chip_enable(priv);
}
#endif /* CONFIG_PM_SLEEP */

--
1.9.1

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