From: Boris Brezillon <redacted>

Commit dca1a4b5ff6e ("clk: at91: keep slow clk enabled to prevent system
hang") added a workaround for the slow clock as it is not properly handled
by its users.

Get and use the slow clock as it is necessary for the timer counters.

Signed-off-by: Boris Brezillon <redacted>
Signed-off-by: Alexandre Belloni <redacted>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
Cc: Daniel Lezcano <redacted>
Cc: Thomas Gleixner <redacted>
Cc: Thierry Reding <redacted>
Cc: linux-pwm at vger.kernel.org

  drivers/clocksource/tcb_clksrc.c |  8 ++++++++
  drivers/misc/atmel_tclib.c       |  4 ++++
  drivers/pwm/pwm-atmel-tcb.c      | 23 ++++++++++++++++-------
  include/linux/atmel_tc.h         |  1 +
  4 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/clocksource/tcb_clksrc.c b/drivers/clocksource/tcb_clksrc.c
index b9b7277173c2..969ba03633b0 100644
--- a/drivers/clocksource/tcb_clksrc.c
+++ b/drivers/clocksource/tcb_clksrc.c

@@ -188,6 +188,13 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
  	ret = clk_prepare_enable(t2_clk);
  	if (ret)
  		return ret;
+
+	ret = clk_prepare_enable(tc->slow_clk);
+	if (ret) {
+		clk_disable_unprepare(t2_clk);
+		return ret;
+	}
+
  	clk_disable(t2_clk);

  	clkevt.regs = tc->regs;

@@ -200,6 +207,7 @@ static int __init setup_clkevents(struct atmel_tc *tc, int clk32k_divisor_idx)
  	ret = request_irq(irq, ch2_irq, IRQF_TIMER, "tc_clkevt", &clkevt);
  	if (ret) {
  		clk_unprepare(t2_clk);
+		clk_disable_unprepare(tc->slow_clk);
  		return ret;
  	}

diff --git a/drivers/misc/atmel_tclib.c b/drivers/misc/atmel_tclib.c
index 0ca05c3ec8d6..ac24a4bd63f7 100644
--- a/drivers/misc/atmel_tclib.c
+++ b/drivers/misc/atmel_tclib.c

@@ -387,9 +387,9 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)

  	tcbpwm = devm_kzalloc(&pdev->dev, sizeof(*tcbpwm), GFP_KERNEL);
  	if (tcbpwm == NULL) {
-		atmel_tc_free(tc);
+		err = -ENOMEM;
  		dev_err(&pdev->dev, "failed to allocate memory\n");
-		return -ENOMEM;
+		goto err_free_tc;
  	}

  	tcbpwm->chip.dev = &pdev->dev;

@@ -400,17 +400,24 @@ static int atmel_tcb_pwm_probe(struct platform_device *pdev)
  	tcbpwm->chip.npwm = NPWM;
  	tcbpwm->tc = tc;

+	err = clk_prepare_enable(tc->slow_clk);
+	if (err)
+		goto err_free_tc;
+
  	spin_lock_init(&tcbpwm->lock);

  	err = pwmchip_add(&tcbpwm->chip);
-	if (err < 0) {
-		atmel_tc_free(tc);
-		return err;
-	}
+	if (err < 0)
+		goto err_free_tc;

  	platform_set_drvdata(pdev, tcbpwm);

  	return 0;
+
+err_free_tc:
+	atmel_tc_free(tc);
+
+	return err;