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pwm: imx-tpm: Count the number of enabled channels in probe

On a soft reset TPM PWM IP may preserve its internal state from previous
runtime, therefore on a subsequent OS boot and driver probe
"enable_count" value and TPM PWM IP internal channels "enabled" states
may get unaligned. In consequence on a suspend/resume cycle the call "if
(--tpm->enable_count == 0)" may lead to "enable_count" overflow the
system being blocked from entering suspend due to:

if (tpm->enable_count > 0)
return -EBUSY;

Fix the problem by counting the enabled channels in probe function.

Signed-off-by: Viorel Suman (OSS) <viorel.suman@oss.nxp.com>
Fixes: 738a1cfec2ed ("pwm: Add i.MX TPM PWM driver support")
Link: https://patch.msgid.link/20260311123309.348904-1-viorel.suman@oss.nxp.com
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

authored by

Viorel Suman (OSS) and committed by
Uwe Kleine-König 3962c24f 6de23f81

+8 -1
+8 -1
drivers/pwm/pwm-imx-tpm.c
··· 352 352 struct clk *clk; 353 353 void __iomem *base; 354 354 int ret; 355 - unsigned int npwm; 355 + unsigned int i, npwm; 356 356 u32 val; 357 357 358 358 base = devm_platform_ioremap_resource(pdev, 0); ··· 381 381 chip->ops = &imx_tpm_pwm_ops; 382 382 383 383 mutex_init(&tpm->lock); 384 + 385 + /* count the enabled channels */ 386 + for (i = 0; i < npwm; ++i) { 387 + val = readl(base + PWM_IMX_TPM_CnSC(i)); 388 + if (FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val)) 389 + ++tpm->enable_count; 390 + } 384 391 385 392 ret = devm_pwmchip_add(&pdev->dev, chip); 386 393 if (ret)