pinctrl: samsung: support a bus clock

On some Samsung-based SoCs there are separate bus clocks / gates each
for each pinctrl instance. To be able to access each pinctrl instance's
registers, this bus clock needs to be running, otherwise register
access will hang. Google Tensor gs101 is one example for such an
implementation.

Update the driver to handle this optional bus clock:
* handle an optional bus clock from DT
* prepare it during driver probe
* enclose all relevant register accesses with a clock enable & disable

Signed-off-by: André Draszik <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Krzysztof Kozlowski <[email protected]>

Author: andred

drivers/pinctrl/samsung/pinctrl-exynos.c

@@ -13,6 +13,7 @@
 // the Samsung pinctrl/gpiolib driver. It also includes the implementation of
 // external gpio and wakeup interrupt support.
 
+#include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/interrupt.h>
 #include <linux/irqdomain.h>
@@ -61,13 +62,21 @@ static void exynos_irq_mask(struct irq_data *irqd)
 	else
 		reg_mask = our_chip->eint_mask + bank->eint_offset;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for masking IRQ\n");
+		return;
+	}
+
 	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	mask = readl(bank->eint_base + reg_mask);
 	mask |= 1 << irqd->hwirq;
 	writel(mask, bank->eint_base + reg_mask);
 
 	raw_spin_unlock_irqrestore(&bank->slock, flags);
+
+	clk_disable(bank->drvdata->pclk);
 }
 
 static void exynos_irq_ack(struct irq_data *irqd)
@@ -82,7 +91,15 @@ static void exynos_irq_ack(struct irq_data *irqd)
 	else
 		reg_pend = our_chip->eint_pend + bank->eint_offset;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock to ack IRQ\n");
+		return;
+	}
+
 	writel(1 << irqd->hwirq, bank->eint_base + reg_pend);
+
+	clk_disable(bank->drvdata->pclk);
 }
 
 static void exynos_irq_unmask(struct irq_data *irqd)
@@ -110,13 +127,21 @@ static void exynos_irq_unmask(struct irq_data *irqd)
 	else
 		reg_mask = our_chip->eint_mask + bank->eint_offset;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for unmasking IRQ\n");
+		return;
+	}
+
 	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	mask = readl(bank->eint_base + reg_mask);
 	mask &= ~(1 << irqd->hwirq);
 	writel(mask, bank->eint_base + reg_mask);
 
 	raw_spin_unlock_irqrestore(&bank->slock, flags);
+
+	clk_disable(bank->drvdata->pclk);
 }
 
 static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
@@ -127,6 +152,7 @@ static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
 	unsigned int shift = EXYNOS_EINT_CON_LEN * irqd->hwirq;
 	unsigned int con, trig_type;
 	unsigned long reg_con;
+	int ret;
 
 	switch (type) {
 	case IRQ_TYPE_EDGE_RISING:
@@ -159,11 +185,20 @@ static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
 	else
 		reg_con = our_chip->eint_con + bank->eint_offset;
 
+	ret = clk_enable(bank->drvdata->pclk);
+	if (ret) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for configuring IRQ type\n");
+		return ret;
+	}
+
 	con = readl(bank->eint_base + reg_con);
 	con &= ~(EXYNOS_EINT_CON_MASK << shift);
 	con |= trig_type << shift;
 	writel(con, bank->eint_base + reg_con);
 
+	clk_disable(bank->drvdata->pclk);
+
 	return 0;
 }
 
@@ -200,6 +235,14 @@ static int exynos_irq_request_resources(struct irq_data *irqd)
 	shift = irqd->hwirq * bank_type->fld_width[PINCFG_TYPE_FUNC];
 	mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;
 
+	ret = clk_enable(bank->drvdata->pclk);
+	if (ret) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for configuring pin %s-%lu\n",
+			bank->name, irqd->hwirq);
+		return ret;
+	}
+
 	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	con = readl(bank->pctl_base + reg_con);
@@ -209,6 +252,8 @@ static int exynos_irq_request_resources(struct irq_data *irqd)
 
 	raw_spin_unlock_irqrestore(&bank->slock, flags);
 
+	clk_disable(bank->drvdata->pclk);
+
 	return 0;
 }
 
@@ -223,6 +268,13 @@ static void exynos_irq_release_resources(struct irq_data *irqd)
 	shift = irqd->hwirq * bank_type->fld_width[PINCFG_TYPE_FUNC];
 	mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for deconfiguring pin %s-%lu\n",
+			bank->name, irqd->hwirq);
+		return;
+	}
+
 	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	con = readl(bank->pctl_base + reg_con);
@@ -232,6 +284,8 @@ static void exynos_irq_release_resources(struct irq_data *irqd)
 
 	raw_spin_unlock_irqrestore(&bank->slock, flags);
 
+	clk_disable(bank->drvdata->pclk);
+
 	gpiochip_unlock_as_irq(&bank->gpio_chip, irqd->hwirq);
 }
 
@@ -281,10 +335,19 @@ static irqreturn_t exynos_eint_gpio_irq(int irq, void *data)
 	unsigned int svc, group, pin;
 	int ret;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for handling IRQ\n");
+		return IRQ_NONE;
+	}
+
 	if (bank->eint_con_offset)
 		svc = readl(bank->eint_base + EXYNOSAUTO_SVC_OFFSET);
 	else
 		svc = readl(bank->eint_base + EXYNOS_SVC_OFFSET);
+
+	clk_disable(bank->drvdata->pclk);
+
 	group = EXYNOS_SVC_GROUP(svc);
 	pin = svc & EXYNOS_SVC_NUM_MASK;
 
@@ -563,6 +626,20 @@ static void exynos_irq_demux_eint16_31(struct irq_desc *desc)
 
 	chained_irq_enter(chip, desc);
 
+	/*
+	 * just enable the clock once here, to avoid an enable/disable dance for
+	 * each bank.
+	 */
+	if (eintd->nr_banks) {
+		struct samsung_pin_bank *b = eintd->banks[0];
+
+		if (clk_enable(b->drvdata->pclk)) {
+			dev_err(b->gpio_chip.parent,
+				"unable to enable clock for pending IRQs\n");
+			return;
+		}
+	}
+
 	for (i = 0; i < eintd->nr_banks; ++i) {
 		struct samsung_pin_bank *b = eintd->banks[i];
 		pend = readl(b->eint_base + b->irq_chip->eint_pend
@@ -572,6 +649,9 @@ static void exynos_irq_demux_eint16_31(struct irq_desc *desc)
 		exynos_irq_demux_eint(pend & ~mask, b->irq_domain);
 	}
 
+	if (eintd->nr_banks)
+		clk_disable(eintd->banks[0]->drvdata->pclk);
+
 	chained_irq_exit(chip, desc);
 }
 
@@ -695,6 +775,12 @@ static void exynos_pinctrl_suspend_bank(
 	struct exynos_eint_gpio_save *save = bank->soc_priv;
 	const void __iomem *regs = bank->eint_base;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for saving state\n");
+		return;
+	}
+
 	save->eint_con = readl(regs + EXYNOS_GPIO_ECON_OFFSET
 						+ bank->eint_offset);
 	save->eint_fltcon0 = readl(regs + EXYNOS_GPIO_EFLTCON_OFFSET
@@ -704,6 +790,8 @@ static void exynos_pinctrl_suspend_bank(
 	save->eint_mask = readl(regs + bank->irq_chip->eint_mask
 						+ bank->eint_offset);
 
+	clk_disable(bank->drvdata->pclk);
+
 	pr_debug("%s: save     con %#010x\n", bank->name, save->eint_con);
 	pr_debug("%s: save fltcon0 %#010x\n", bank->name, save->eint_fltcon0);
 	pr_debug("%s: save fltcon1 %#010x\n", bank->name, save->eint_fltcon1);
@@ -716,9 +804,17 @@ static void exynosauto_pinctrl_suspend_bank(struct samsung_pinctrl_drv_data *drv
 	struct exynos_eint_gpio_save *save = bank->soc_priv;
 	const void __iomem *regs = bank->eint_base;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for saving state\n");
+		return;
+	}
+
 	save->eint_con = readl(regs + bank->pctl_offset + bank->eint_con_offset);
 	save->eint_mask = readl(regs + bank->pctl_offset + bank->eint_mask_offset);
 
+	clk_disable(bank->drvdata->pclk);
+
 	pr_debug("%s: save     con %#010x\n", bank->name, save->eint_con);
 	pr_debug("%s: save    mask %#010x\n", bank->name, save->eint_mask);
 }
@@ -753,6 +849,12 @@ static void exynos_pinctrl_resume_bank(
 	struct exynos_eint_gpio_save *save = bank->soc_priv;
 	void __iomem *regs = bank->eint_base;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for restoring state\n");
+		return;
+	}
+
 	pr_debug("%s:     con %#010x => %#010x\n", bank->name,
 			readl(regs + EXYNOS_GPIO_ECON_OFFSET
 			+ bank->eint_offset), save->eint_con);
@@ -774,6 +876,8 @@ static void exynos_pinctrl_resume_bank(
 						+ 2 * bank->eint_offset + 4);
 	writel(save->eint_mask, regs + bank->irq_chip->eint_mask
 						+ bank->eint_offset);
+
+	clk_disable(bank->drvdata->pclk);
 }
 
 static void exynosauto_pinctrl_resume_bank(struct samsung_pinctrl_drv_data *drvdata,
@@ -782,13 +886,21 @@ static void exynosauto_pinctrl_resume_bank(struct samsung_pinctrl_drv_data *drvd
 	struct exynos_eint_gpio_save *save = bank->soc_priv;
 	void __iomem *regs = bank->eint_base;
 
+	if (clk_enable(bank->drvdata->pclk)) {
+		dev_err(bank->gpio_chip.parent,
+			"unable to enable clock for restoring state\n");
+		return;
+	}
+
 	pr_debug("%s:     con %#010x => %#010x\n", bank->name,
 		 readl(regs + bank->pctl_offset + bank->eint_con_offset), save->eint_con);
 	pr_debug("%s:    mask %#010x => %#010x\n", bank->name,
 		 readl(regs + bank->pctl_offset + bank->eint_mask_offset), save->eint_mask);
 
 	writel(save->eint_con, regs + bank->pctl_offset + bank->eint_con_offset);
 	writel(save->eint_mask, regs + bank->pctl_offset + bank->eint_mask_offset);
+
+	clk_disable(bank->drvdata->pclk);
 }
 
 void exynos_pinctrl_resume(struct samsung_pinctrl_drv_data *drvdata)