pwm: imx-tpm: fix probe crash due to access registers without clock

The following commit abf6569 ("pwm: imx-tpm: Make use of
devm_pwmchip_alloc() function") introduced an issue that accessing
registers without clock which results in the following boot crash
on MX7ULP platform. Fixed it by enabling clock properly.

Unhandled fault: external abort on non-linefetch (0x1008) at 0xf0978004
[f0978004] *pgd=64009811, *pte=40250653, *ppte=40250453
Internal error: : 1008 [#1] SMP ARM
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.8.0-rc6-next-20240301 #18
Hardware name: Freescale i.MX7ULP (Device Tree)
PC is at pwm_imx_tpm_probe+0x1c/0xd8
LR is at __devm_ioremap_resource+0xf8/0x1dc
pc : [<c0629e58>]    lr : [<c0562d4c>]    psr: 80000053
sp : f0825e10  ip : 00000000  fp : 00000000
r10: c148f8c0  r9 : c41fc338  r8 : c164b000
r7 : 00000000  r6 : c406b400  r5 : c406b410  r4 : f0978000
r3 : 00000005  r2 : 00000000  r1 : a0000053  r0 : f0978000
Flags: Nzcv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment none
Control: 10c5387d  Table: 6000406a  DAC: 00000051
...
Call trace:
 pwm_imx_tpm_probe from platform_probe+0x58/0xb0
 platform_probe from really_probe+0xc4/0x2e0
 really_probe from __driver_probe_device+0x84/0x19c
 __driver_probe_device from driver_probe_device+0x2c/0x104
 driver_probe_device from __driver_attach+0x90/0x170
 __driver_attach from bus_for_each_dev+0x7c/0xd0
 bus_for_each_dev from bus_add_driver+0xc4/0x1cc
 bus_add_driver from driver_register+0x7c/0x114
 driver_register from do_one_initcall+0x58/0x270
 do_one_initcall from kernel_init_freeable+0x170/0x218
 kernel_init_freeable from kernel_init+0x14/0x140
 kernel_init from ret_from_fork+0x14/0x20

Fixes: abf6569 ("pwm: imx-tpm: Make use of devm_pwmchip_alloc() function")
Signed-off-by: Dong Aisheng <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Uwe Kleine-König <[email protected]>
Origin: v6.9-rc1~146^2, commit:dd6c6d57ab61d496f6ff7d6ca38611062af142a1
(cherry picked from commit 285f32a)

Author: Dong Aisheng

drivers/pwm/pwm-imx-tpm.c

@@ -337,6 +337,7 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev)
 {
 	struct pwm_chip *chip;
 	struct imx_tpm_pwm_chip *tpm;
+	struct clk *clk;
 	void __iomem *base;
 	int ret;
 	unsigned int npwm;
@@ -346,6 +347,11 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev)
 	if (IS_ERR(base))
 		return PTR_ERR(base);
 
+	clk = devm_clk_get_enabled(&pdev->dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(clk),
+				     "failed to get PWM clock\n");
+
 	/* get number of channels */
 	val = readl(base + PWM_IMX_TPM_PARAM);
 	npwm = FIELD_GET(PWM_IMX_TPM_PARAM_CHAN, val);
@@ -358,11 +364,7 @@ static int pwm_imx_tpm_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, tpm);
 
 	tpm->base = base;
-
-	tpm->clk = devm_clk_get_enabled(&pdev->dev, NULL);
-	if (IS_ERR(tpm->clk))
-		return dev_err_probe(&pdev->dev, PTR_ERR(tpm->clk),
-				     "failed to get PWM clock\n");
+	tpm->clk = clk;
 
 	chip->ops = &imx_tpm_pwm_ops;