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Commit 51fc9d44 authored by Girish Mahadevan's avatar Girish Mahadevan
Browse files

serial: msm_geni_serial: Add checks against autosuspend 



The framework functions implemented in the driver checks if the runtime
status of the device is active before attempting to access the core's
register space.
But if there is a pending autosuspend, then the runtime status will still
be active and it is possible for the core resources to be pulled away
while a framework function is attempting to access the core's registers.
This can crash the device.

In any control path pertaining to Rx or Tx detect a pending autosuspend
and bail out. This shouldn't cause any side-effects, if the function is
needed for a port close/cleanup the driver will call it after putting in
the correct runtime vote. So a framework call to do the same can be
ignored if there is a pending suspend.

In data path however, things are different, as a userspace write doesn't
block but an ioctl to vote clocks off will. So there is no guarantee of
order between a transmit (write from userspace) and a clock off request.
In such cases, add an additional check in the ioctl call to query the
framework buffer and any inflight transactions and delay before actually
removing the runtime vote.
Also when there is a framework call to transmit data, immediately put a
runtime vote in which is removed only when that transaction has completed.

Change-Id: I43bdc1ecb234e406bcd31c1296dec2ae379ef83b
Signed-off-by: default avatarGirish Mahadevan <girishm@codeaurora.org>
parent efb8f6ef

drivers/tty/serial/msm_geni_serial.c

+84 −25
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ 
#define WAIT_XFER_MAX_TIMEOUT_US	(10000)

#define WAIT_XFER_MIN_TIMEOUT_US	(9000)

#define IPC_LOG_PWR_PAGES	(6)

#define IPC_LOG_MISC_PAGES	(6)

#define IPC_LOG_MISC_PAGES	(10)

#define IPC_LOG_TX_RX_PAGES	(8)

#define DATA_BYTES_PER_LINE	(32)
@@ -242,26 +242,40 @@ static void dump_ipc(void *ipc_ctx, char *prefix, char *string, 
					(unsigned int)addr, size, buf);

}



static bool device_pending_suspend(struct uart_port *uport)

{

	int usage_count = atomic_read(&uport->dev->power.usage_count);



	return (pm_runtime_suspended(uport->dev) || !usage_count);

}



static bool check_transfers_inflight(struct uart_port *uport)

{

	bool xfer_on = false;

	bool tx_active = false;

	bool tx_empty = false;

	bool tx_fifo_status = false;

	bool m_cmd_active = false;

	bool rx_active = false;

	u32 rx_fifo_status = 0;

	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);

	u32 geni_status = geni_read_reg_nolog(uport->membase,

						SE_GENI_STATUS);

	struct circ_buf *xmit = &uport->state->xmit;



	/* Possible stop tx is called multiple times. */

	m_cmd_active = geni_status & M_GENI_CMD_ACTIVE;

	tx_empty = msm_geni_serial_tx_empty(uport);

	tx_active = m_cmd_active || !tx_empty;

	if (port->xfer_mode == SE_DMA)

		tx_fifo_status = port->tx_dma ? 1 : 0;

	else

		tx_fifo_status = geni_read_reg_nolog(uport->membase,

						SE_GENI_TX_FIFO_STATUS);

	tx_active = m_cmd_active || tx_fifo_status;

	rx_fifo_status = geni_read_reg_nolog(uport->membase,

						SE_GENI_RX_FIFO_STATUS);

	if (rx_fifo_status)

		rx_active = true;



	if (rx_active || tx_active)

	if (rx_active || tx_active || !uart_circ_empty(xmit))

		xfer_on = true;



	return xfer_on;
@@ -330,6 +344,7 @@ static int vote_clock_off(struct uart_port *uport) 
				__func__, port->ioctl_count);

		return -EPERM;

	}

	wait_for_transfers_inflight(uport);

	port->ioctl_count--;

	msm_geni_serial_power_off(uport);

	IPC_LOG_MSG(port->ipc_log_pwr, "%s%s ioctl %d\n", __func__,
@@ -363,8 +378,13 @@ static int msm_geni_serial_ioctl(struct uart_port *uport, unsigned int cmd, 


static void msm_geni_serial_break_ctl(struct uart_port *uport, int ctl)

{

	if (!uart_console(uport) && pm_runtime_status_suspended(uport->dev))

	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);



	if (!uart_console(uport) && device_pending_suspend(uport)) {

		IPC_LOG_MSG(port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);

		return;

	}



	if (ctl) {

		wait_for_transfers_inflight(uport);
@@ -385,9 +405,13 @@ static unsigned int msm_geni_serial_get_mctrl(struct uart_port *uport) 
{

	u32 geni_ios = 0;

	unsigned int mctrl = TIOCM_DSR | TIOCM_CAR;

	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);



	if (pm_runtime_status_suspended(uport->dev))

	if (device_pending_suspend(uport)) {

		IPC_LOG_MSG(port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);

		return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;

	}



	geni_ios = geni_read_reg_nolog(uport->membase, SE_GENI_IOS);

	if (!(geni_ios & IO2_DATA_IN))
@@ -405,9 +429,13 @@ static void msm_geni_serial_set_mctrl(struct uart_port *uport, 
							unsigned int mctrl)

{

	u32 uart_manual_rfr = 0;

	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);



	if (pm_runtime_status_suspended(uport->dev))

	if (device_pending_suspend(uport)) {

		IPC_LOG_MSG(port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);

		return;

	}

	if (!(mctrl & TIOCM_RTS))

		uart_manual_rfr |= (UART_MANUAL_RFR_EN | UART_RFR_NOT_READY);

	geni_write_reg_nolog(uart_manual_rfr, uport->membase,
@@ -457,6 +485,14 @@ static int msm_geni_serial_power_on(struct uart_port *uport) 


static void msm_geni_serial_power_off(struct uart_port *uport)

{

	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);

	int usage_count = atomic_read(&uport->dev->power.usage_count);



	if (!usage_count) {

		IPC_LOG_MSG(port->ipc_log_pwr, "%s: Usage Count is already 0\n",

								__func__);

		return;

	}

	pm_runtime_mark_last_busy(uport->dev);

	pm_runtime_put_autosuspend(uport->dev);

}
@@ -791,13 +827,16 @@ static void msm_geni_serial_start_tx(struct uart_port *uport) 
	unsigned int geni_status;

	unsigned int geni_ios;



	if (!uart_console(uport) && pm_runtime_status_suspended(uport->dev)) {

		dev_err(uport->dev, "%s.Device is suspended.\n", __func__);

	if (!uart_console(uport) && !pm_runtime_active(uport->dev)) {

		IPC_LOG_MSG(msm_port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);

		return;

				"%s.Putting in async RPM vote\n", __func__);

		pm_runtime_get(uport->dev);

		goto exit_start_tx;

	}



	if (!uart_console(uport))

		pm_runtime_get(uport->dev);



	if (msm_port->xfer_mode == FIFO_MODE) {

		geni_status = geni_read_reg_nolog(uport->membase,

						  SE_GENI_STATUS);
@@ -830,6 +869,9 @@ static void msm_geni_serial_start_tx(struct uart_port *uport) 
	if (!(geni_ios & IO2_DATA_IN))

		IPC_LOG_MSG(msm_port->ipc_log_misc, "%s: ios: 0x%08x\n",

							__func__, geni_ios);

exit_start_tx:

	if (!uart_console(uport))

		msm_geni_serial_power_off(uport);

}



static void msm_geni_serial_tx_fsm_rst(struct uart_port *uport)
@@ -857,7 +899,7 @@ static void msm_geni_serial_stop_tx(struct uart_port *uport) 
	unsigned int geni_status;

	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);



	if (!uart_console(uport) && pm_runtime_status_suspended(uport->dev)) {

	if (!uart_console(uport) && device_pending_suspend(uport)) {

		dev_err(uport->dev, "%s.Device is suspended.\n", __func__);

		IPC_LOG_MSG(port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);
@@ -909,7 +951,7 @@ static void msm_geni_serial_start_rx(struct uart_port *uport) 
	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);

	int ret;



	if (!uart_console(uport) && pm_runtime_status_suspended(uport->dev)) {

	if (!uart_console(uport) && device_pending_suspend(uport)) {

		dev_err(uport->dev, "%s.Device is suspended.\n", __func__);

		IPC_LOG_MSG(port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);
@@ -942,7 +984,7 @@ static void msm_geni_serial_start_rx(struct uart_port *uport) 
			dev_err(uport->dev, "%s: RX Prep dma failed %d\n",

				__func__, ret);

			msm_geni_serial_stop_rx(uport);

			return;

			goto exit_geni_serial_start_rx;

		}

	}

	/*
@@ -951,6 +993,7 @@ static void msm_geni_serial_start_rx(struct uart_port *uport) 
	 */

	mb();

	geni_status = geni_read_reg_nolog(uport->membase, SE_GENI_STATUS);

exit_geni_serial_start_rx:

	IPC_LOG_MSG(port->ipc_log_misc, "%s 0x%x\n", __func__, geni_status);

}
@@ -981,8 +1024,7 @@ static void msm_geni_serial_stop_rx(struct uart_port *uport) 
	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);

	u32 irq_clear = S_CMD_DONE_EN;



	if (!uart_console(uport) && pm_runtime_status_suspended(uport->dev)) {

		dev_err(uport->dev, "%s.Device is suspended.\n", __func__);

	if (!uart_console(uport) && device_pending_suspend(uport)) {

		IPC_LOG_MSG(port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);

		return;
@@ -1110,6 +1152,15 @@ static int msm_geni_serial_handle_tx(struct uart_port *uport) 
	tx_fifo_status = geni_read_reg_nolog(uport->membase,

					SE_GENI_TX_FIFO_STATUS);

	if (uart_circ_empty(xmit) && !tx_fifo_status) {

		/*

		 * This will balance out the power vote put in during start_tx

		 * allowing the device to suspend.

		 */

		if (!uart_console(uport)) {

			IPC_LOG_MSG(msm_port->ipc_log_misc,

				"%s.Power Off.\n", __func__);

			msm_geni_serial_power_off(uport);

		}

		msm_geni_serial_stop_tx(uport);

		goto exit_handle_tx;

	}
@@ -1166,7 +1217,6 @@ static int msm_geni_serial_handle_tx(struct uart_port *uport) 
		msm_port->xmit_size = xmit_size;

	}

exit_handle_tx:

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)

	uart_write_wakeup(uport);

	return ret;

}
@@ -1234,8 +1284,18 @@ static int msm_geni_serial_handle_dma_tx(struct uart_port *uport) 


	if (!uart_circ_empty(xmit))

		msm_geni_serial_prep_dma_tx(uport);

	else

	else {

		/*

		 * This will balance out the power vote put in during start_tx

		 * allowing the device to suspend.

		 */

		if (!uart_console(uport)) {

			IPC_LOG_MSG(msm_port->ipc_log_misc,

				"%s.Power Off.\n", __func__);

			msm_geni_serial_power_off(uport);

		}

		uart_write_wakeup(uport);

	}

	return 0;

}
@@ -1255,7 +1315,7 @@ static irqreturn_t msm_geni_serial_isr(int isr, void *dev) 
	spin_lock_irqsave(&uport->lock, flags);

	if (uart_console(uport) && uport->suspended)

		goto exit_geni_serial_isr;

	if (!uart_console(uport) && pm_runtime_status_suspended(uport->dev)) {

	if (!uart_console(uport) && pm_runtime_suspended(uport->dev)) {

		dev_err(uport->dev, "%s.Device is suspended.\n", __func__);

		IPC_LOG_MSG(msm_port->ipc_log_misc,

				"%s.Device is suspended.\n", __func__);
@@ -1793,10 +1853,10 @@ static unsigned int msm_geni_serial_tx_empty(struct uart_port *uport) 
	unsigned int is_tx_empty = 1;

	struct msm_geni_serial_port *port = GET_DEV_PORT(uport);



	if (!uart_console(uport) && pm_runtime_status_suspended(uport->dev)) {

	if (!uart_console(uport) && device_pending_suspend(uport)) {

		IPC_LOG_MSG(port->ipc_log_pwr,

			"%s Device suspended,vote clocks on.\n", __func__);

		return 1;

		return 0;

	}



	if (port->xfer_mode == SE_DMA)
@@ -2099,7 +2159,6 @@ static void msm_geni_serial_debug_init(struct uart_port *uport, bool console) 
			if (!msm_port->ipc_log_misc)

				dev_info(uport->dev, "Err in Misc IPC Log\n");

		}



	}

}
@@ -2356,12 +2415,12 @@ static int msm_geni_serial_runtime_suspend(struct device *dev) 
	int ret = 0;



	wait_for_transfers_inflight(&port->uport);

	disable_irq(port->uport.irq);

	ret = se_geni_resources_off(&port->serial_rsc);

	if (ret) {

		dev_err(dev, "%s: Error ret %d\n", __func__, ret);

		goto exit_runtime_suspend;

	}

	disable_irq(port->uport.irq);

	if (port->wakeup_irq > 0) {

		struct se_geni_rsc *rsc = &port->serial_rsc;