x86/platform/intel/pmc_atom: Export accessors to PMC registers

Export the pmc_atom_read() and pmc_atom_write() accessors to the PMC
registers. On early initcall stages the functions will return
-ENODEV, and caller has to wait when it will be available.

Additionally make absence of debugfs a non-fatal error.

The patch will be useful for the upcoming fixes regarding to the
LPSS block found on Intel BayTrail-T and Braswell.

Signed-off-by: Andy Shevchenko <[e-mail]>
Cc: Aubrey Li <[e-mail]>
Cc: Kumar P Mahesh <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Rafael J . Wysocki <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/pmc_atom.h

···
 #define	SLEEP_TYPE_MASK		0xFFFFECFF
 #define	SLEEP_TYPE_S5		0x1C00
 #define	SLEEP_ENABLE		0x2000
+
+extern int pmc_atom_read(int offset, u32 *value);
+extern int pmc_atom_write(int offset, u32 value);
+
 #endif /* PMC_ATOM_H */

arch/x86/kernel/pmc_atom.c

···
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *dbgfs_dir;
 #endif /* CONFIG_DEBUG_FS */
+	bool init;
 };
 
 static struct pmc_dev pmc_device;
···
 {
 	writel(val, pmc->regmap + reg_offset);
 }
+
+int pmc_atom_read(int offset, u32 *value)
+{
+	struct pmc_dev *pmc = &pmc_device;
+
+	if (!pmc->init)
+		return -ENODEV;
+
+	*value = pmc_reg_read(pmc, offset);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pmc_atom_read);
+
+int pmc_atom_write(int offset, u32 value)
+{
+	struct pmc_dev *pmc = &pmc_device;
+
+	if (!pmc->init)
+		return -ENODEV;
+
+	pmc_reg_write(pmc, offset, value);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pmc_atom_write);
 
 static void pmc_power_off(void)
 {
···
 	debugfs_remove_recursive(pmc->dbgfs_dir);
 }
 
-static int pmc_dbgfs_register(struct pmc_dev *pmc, struct pci_dev *pdev)
+static int pmc_dbgfs_register(struct pmc_dev *pmc)
 {
 	struct dentry *dir, *f;
 
···
 
 	f = debugfs_create_file("dev_state", S_IFREG | S_IRUGO,
 				dir, pmc, &pmc_dev_state_ops);
-	if (!f) {
-		dev_err(&pdev->dev, "dev_state register failed\n");
+	if (!f)
 		goto err;
-	}
 
 	f = debugfs_create_file("pss_state", S_IFREG | S_IRUGO,
 				dir, pmc, &pmc_pss_state_ops);
-	if (!f) {
-		dev_err(&pdev->dev, "pss_state register failed\n");
+	if (!f)
 		goto err;
-	}
 
 	f = debugfs_create_file("sleep_state", S_IFREG | S_IRUGO,
 				dir, pmc, &pmc_sleep_tmr_ops);
-	if (!f) {
-		dev_err(&pdev->dev, "sleep_state register failed\n");
+	if (!f)
 		goto err;
-	}
 
 	return 0;
 err:
···
 	return -ENODEV;
 }
 #else
-static int pmc_dbgfs_register(struct pmc_dev *pmc, struct pci_dev *pdev)
+static int pmc_dbgfs_register(struct pmc_dev *pmc)
 {
 	return 0;
 }
···
 	/* PMC hardware registers setup */
 	pmc_hw_reg_setup(pmc);
 
-	ret = pmc_dbgfs_register(pmc, pdev);
-	if (ret) {
-		iounmap(pmc->regmap);
-	}
+	ret = pmc_dbgfs_register(pmc);
+	if (ret)
+		dev_warn(&pdev->dev, "debugfs register failed\n");
 
+	pmc->init = true;
 	return ret;
 }