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Date:   Sun,  3 Jan 2021 05:06:33 -0600
From:   Samuel Holland <samuel@...lland.org>
To:     Maxime Ripard <mripard@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Ondrej Jirman <megous@...ous.com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com, Samuel Holland <samuel@...lland.org>
Subject: [PATCH 2/4] bus: sunxi-rsb: Split out controller init/exit functions

This separates the resource acquisition from the hardware initialization
phase, so the hardware initialization can be repeated after system
suspend/resume. The same is done for the exit/remove function, except
that there is no resource deallocation phase due to the use of devres.

The requested RSB clock frequency is stored in `struct sunxi_rsb` so it
will be available when reinitializing the hardware.

Signed-off-by: Samuel Holland <samuel@...lland.org>
---
 drivers/bus/sunxi-rsb.c | 127 ++++++++++++++++++++++------------------
 1 file changed, 71 insertions(+), 56 deletions(-)

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index c13340cab27a..3f290da45619 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -126,6 +126,7 @@ struct sunxi_rsb {
 	struct completion complete;
 	struct mutex lock;
 	unsigned int status;
+	u32 clk_freq;
 };
 
 /* bus / slave device related functions */
@@ -614,16 +615,74 @@ static int of_rsb_register_devices(struct sunxi_rsb *rsb)
 	return 0;
 }
 
+static int sunxi_rsb_hw_init(struct sunxi_rsb *rsb)
+{
+	struct device *dev = rsb->dev;
+	unsigned long p_clk_freq;
+	u32 clk_delay, reg;
+	int clk_div, ret;
+
+	ret = clk_prepare_enable(rsb->clk);
+	if (ret) {
+		dev_err(dev, "failed to enable clk: %d\n", ret);
+		return ret;
+	}
+
+	ret = reset_control_deassert(rsb->rstc);
+	if (ret) {
+		dev_err(dev, "failed to deassert reset line: %d\n", ret);
+		goto err_clk_disable;
+	}
+
+	/* reset the controller */
+	writel(RSB_CTRL_SOFT_RST, rsb->regs + RSB_CTRL);
+	readl_poll_timeout(rsb->regs + RSB_CTRL, reg,
+			   !(reg & RSB_CTRL_SOFT_RST), 1000, 100000);
+
+	/*
+	 * Clock frequency and delay calculation code is from
+	 * Allwinner U-boot sources.
+	 *
+	 * From A83 user manual:
+	 * bus clock frequency = parent clock frequency / (2 * (divider + 1))
+	 */
+	p_clk_freq = clk_get_rate(rsb->clk);
+	clk_div = p_clk_freq / rsb->clk_freq / 2;
+	if (!clk_div)
+		clk_div = 1;
+	else if (clk_div > RSB_CCR_MAX_CLK_DIV + 1)
+		clk_div = RSB_CCR_MAX_CLK_DIV + 1;
+
+	clk_delay = clk_div >> 1;
+	if (!clk_delay)
+		clk_delay = 1;
+
+	dev_info(dev, "RSB running at %lu Hz\n", p_clk_freq / clk_div / 2);
+	writel(RSB_CCR_SDA_OUT_DELAY(clk_delay) | RSB_CCR_CLK_DIV(clk_div - 1),
+	       rsb->regs + RSB_CCR);
+
+	return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(rsb->clk);
+
+	return ret;
+}
+
+static void sunxi_rsb_hw_exit(struct sunxi_rsb *rsb)
+{
+	reset_control_assert(rsb->rstc);
+	clk_disable_unprepare(rsb->clk);
+}
+
 static int sunxi_rsb_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct resource *r;
 	struct sunxi_rsb *rsb;
-	unsigned long p_clk_freq;
-	u32 clk_delay, clk_freq = 3000000;
-	int clk_div, irq, ret;
-	u32 reg;
+	u32 clk_freq = 3000000;
+	int irq, ret;
 
 	of_property_read_u32(np, "clock-frequency", &clk_freq);
 	if (clk_freq > RSB_MAX_FREQ) {
@@ -638,6 +697,7 @@ static int sunxi_rsb_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	rsb->dev = dev;
+	rsb->clk_freq = clk_freq;
 	platform_set_drvdata(pdev, rsb);
 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	rsb->regs = devm_ioremap_resource(dev, r);
@@ -655,63 +715,27 @@ static int sunxi_rsb_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = clk_prepare_enable(rsb->clk);
-	if (ret) {
-		dev_err(dev, "failed to enable clk: %d\n", ret);
-		return ret;
-	}
-
-	p_clk_freq = clk_get_rate(rsb->clk);
-
 	rsb->rstc = devm_reset_control_get(dev, NULL);
 	if (IS_ERR(rsb->rstc)) {
 		ret = PTR_ERR(rsb->rstc);
 		dev_err(dev, "failed to retrieve reset controller: %d\n", ret);
-		goto err_clk_disable;
-	}
-
-	ret = reset_control_deassert(rsb->rstc);
-	if (ret) {
-		dev_err(dev, "failed to deassert reset line: %d\n", ret);
-		goto err_clk_disable;
+		return ret;
 	}
 
 	init_completion(&rsb->complete);
 	mutex_init(&rsb->lock);
 
-	/* reset the controller */
-	writel(RSB_CTRL_SOFT_RST, rsb->regs + RSB_CTRL);
-	readl_poll_timeout(rsb->regs + RSB_CTRL, reg,
-			   !(reg & RSB_CTRL_SOFT_RST), 1000, 100000);
-
-	/*
-	 * Clock frequency and delay calculation code is from
-	 * Allwinner U-boot sources.
-	 *
-	 * From A83 user manual:
-	 * bus clock frequency = parent clock frequency / (2 * (divider + 1))
-	 */
-	clk_div = p_clk_freq / clk_freq / 2;
-	if (!clk_div)
-		clk_div = 1;
-	else if (clk_div > RSB_CCR_MAX_CLK_DIV + 1)
-		clk_div = RSB_CCR_MAX_CLK_DIV + 1;
-
-	clk_delay = clk_div >> 1;
-	if (!clk_delay)
-		clk_delay = 1;
-
-	dev_info(dev, "RSB running at %lu Hz\n", p_clk_freq / clk_div / 2);
-	writel(RSB_CCR_SDA_OUT_DELAY(clk_delay) | RSB_CCR_CLK_DIV(clk_div - 1),
-	       rsb->regs + RSB_CCR);
-
 	ret = devm_request_irq(dev, irq, sunxi_rsb_irq, 0, RSB_CTRL_NAME, rsb);
 	if (ret) {
 		dev_err(dev, "can't register interrupt handler irq %d: %d\n",
 			irq, ret);
-		goto err_reset_assert;
+		return ret;
 	}
 
+	ret = sunxi_rsb_hw_init(rsb);
+	if (ret)
+		return ret;
+
 	/* initialize all devices on the bus into RSB mode */
 	ret = sunxi_rsb_init_device_mode(rsb);
 	if (ret)
@@ -720,14 +744,6 @@ static int sunxi_rsb_probe(struct platform_device *pdev)
 	of_rsb_register_devices(rsb);
 
 	return 0;
-
-err_reset_assert:
-	reset_control_assert(rsb->rstc);
-
-err_clk_disable:
-	clk_disable_unprepare(rsb->clk);
-
-	return ret;
 }
 
 static int sunxi_rsb_remove(struct platform_device *pdev)
@@ -735,8 +751,7 @@ static int sunxi_rsb_remove(struct platform_device *pdev)
 	struct sunxi_rsb *rsb = platform_get_drvdata(pdev);
 
 	device_for_each_child(rsb->dev, NULL, sunxi_rsb_remove_devices);
-	reset_control_assert(rsb->rstc);
-	clk_disable_unprepare(rsb->clk);
+	sunxi_rsb_hw_exit(rsb);
 
 	return 0;
 }
-- 
2.26.2

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