mmc: meson-mx-sdio: Refactor internal clock initialization

Use modern common clock framework helpers for simplifying the clock
controller management:
- switch to struct clk_hw for internal clocks and only get the
  "cfg_div_clk" (which has to be managed at runtime) as struct clk
  using devm_clk_hw_get_clk() which is then the only clock used by
  struct meson_mx_mmc_host.
- use CLK_HW_INIT_FW_NAME and CLK_HW_INIT_HW helper macros for simpler
  init data initialization
- keep the clock controller memory allocation separate to prevent a
  potential use-after-free because struct meson_mx_mmc_host_clkc is
  free'd before controller_dev

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: xdarklight

drivers/mmc/host/meson-mx-sdio.c

@@ -99,15 +99,15 @@
 #define MESON_MX_SDIO_RESPONSE_CRC16_BITS			(16 - 1)
 #define MESON_MX_SDIO_MAX_SLOTS					3
 
+struct meson_mx_mmc_host_clkc {
+	struct clk_divider		cfg_div;
+	struct clk_fixed_factor		fixed_div2;
+};
+
 struct meson_mx_mmc_host {
 	struct device			*controller_dev;
 
-	struct clk			*parent_clk;
-	struct clk_divider		cfg_div;
 	struct clk			*cfg_div_clk;
-	struct clk_fixed_factor		fixed_factor;
-	struct clk			*fixed_factor_clk;
-
 	struct regmap			*regmap;
 	int				irq;
 	spinlock_t			irq_lock;
@@ -548,8 +548,7 @@ static int meson_mx_mmc_add_host(struct meson_mx_mmc_host *host)
 
 	/* Get the min and max supported clock rates */
 	mmc->f_min = clk_round_rate(host->cfg_div_clk, 1);
-	mmc->f_max = clk_round_rate(host->cfg_div_clk,
-				    clk_get_rate(host->parent_clk));
+	mmc->f_max = clk_round_rate(host->cfg_div_clk, ULONG_MAX);
 
 	mmc->caps |= MMC_CAP_CMD23 | MMC_CAP_WAIT_WHILE_BUSY;
 	mmc->ops = &meson_mx_mmc_ops;
@@ -565,54 +564,62 @@ static int meson_mx_mmc_add_host(struct meson_mx_mmc_host *host)
 	return 0;
 }
 
-static int meson_mx_mmc_register_clks(struct meson_mx_mmc_host *host,
-				      void __iomem *base)
+static struct clk *meson_mx_mmc_register_clk(struct device *dev,
+					     void __iomem *base)
 {
-	struct clk_init_data init;
-	const char *clk_div_parent, *clk_fixed_factor_parent;
-
-	clk_fixed_factor_parent = __clk_get_name(host->parent_clk);
-	init.name = devm_kasprintf(host->controller_dev, GFP_KERNEL,
-				   "%s#fixed_factor",
-				   dev_name(host->controller_dev));
-	if (!init.name)
-		return -ENOMEM;
+	const char *fixed_div2_name, *cfg_div_name;
+	struct meson_mx_mmc_host_clkc *host_clkc;
+	struct clk *clk;
+	int ret;
 
-	init.ops = &clk_fixed_factor_ops;
-	init.flags = 0;
-	init.parent_names = &clk_fixed_factor_parent;
-	init.num_parents = 1;
-	host->fixed_factor.div = 2;
-	host->fixed_factor.mult = 1;
-	host->fixed_factor.hw.init = &init;
-
-	host->fixed_factor_clk = devm_clk_register(host->controller_dev,
-						 &host->fixed_factor.hw);
-	if (WARN_ON(IS_ERR(host->fixed_factor_clk)))
-		return PTR_ERR(host->fixed_factor_clk);
-
-	clk_div_parent = __clk_get_name(host->fixed_factor_clk);
-	init.name = devm_kasprintf(host->controller_dev, GFP_KERNEL,
-				   "%s#div", dev_name(host->controller_dev));
-	if (!init.name)
-		return -ENOMEM;
+	/* use a dedicated memory allocation for the clock controller to
+	 * prevent use-after-free as meson_mx_mmc_host is free'd before
+	 * dev (controller dev, not mmc_host->dev) is free'd.
+	 */
+	host_clkc = devm_kzalloc(dev, sizeof(*host_clkc), GFP_KERNEL);
+	if (!host_clkc)
+		return ERR_PTR(-ENOMEM);
+
+	fixed_div2_name = devm_kasprintf(dev, GFP_KERNEL, "%s#fixed_div2",
+					 dev_name(dev));
+	if (!fixed_div2_name)
+		return ERR_PTR(-ENOMEM);
+
+	host_clkc->fixed_div2.div = 2;
+	host_clkc->fixed_div2.mult = 1;
+	host_clkc->fixed_div2.hw.init = CLK_HW_INIT_FW_NAME(fixed_div2_name,
+							    "clkin",
+							    &clk_fixed_factor_ops,
+							    0);
+	ret = devm_clk_hw_register(dev, &host_clkc->fixed_div2.hw);
+	if (ret)
+		return dev_err_ptr_probe(dev, ret,
+					 "Failed to register %s clock\n",
+					 fixed_div2_name);
+
+	cfg_div_name = devm_kasprintf(dev, GFP_KERNEL, "%s#div", dev_name(dev));
+	if (!cfg_div_name)
+		return ERR_PTR(-ENOMEM);
+
+	host_clkc->cfg_div.reg = base + MESON_MX_SDIO_CONF;
+	host_clkc->cfg_div.shift = MESON_MX_SDIO_CONF_CMD_CLK_DIV_SHIFT;
+	host_clkc->cfg_div.width = MESON_MX_SDIO_CONF_CMD_CLK_DIV_WIDTH;
+	host_clkc->cfg_div.hw.init = CLK_HW_INIT_HW(cfg_div_name,
+						    &host_clkc->fixed_div2.hw,
+						    &clk_divider_ops,
+						    CLK_DIVIDER_ALLOW_ZERO);
+	ret = devm_clk_hw_register(dev, &host_clkc->cfg_div.hw);
+	if (ret)
+		return dev_err_ptr_probe(dev, ret,
+					 "Failed to register %s clock\n",
+					 cfg_div_name);
 
-	init.ops = &clk_divider_ops;
-	init.flags = CLK_SET_RATE_PARENT;
-	init.parent_names = &clk_div_parent;
-	init.num_parents = 1;
-	host->cfg_div.reg = base + MESON_MX_SDIO_CONF;
-	host->cfg_div.shift = MESON_MX_SDIO_CONF_CMD_CLK_DIV_SHIFT;
-	host->cfg_div.width = MESON_MX_SDIO_CONF_CMD_CLK_DIV_WIDTH;
-	host->cfg_div.hw.init = &init;
-	host->cfg_div.flags = CLK_DIVIDER_ALLOW_ZERO;
-
-	host->cfg_div_clk = devm_clk_register(host->controller_dev,
-					      &host->cfg_div.hw);
-	if (WARN_ON(IS_ERR(host->cfg_div_clk)))
-		return PTR_ERR(host->cfg_div_clk);
+	clk = devm_clk_hw_get_clk(dev, &host_clkc->cfg_div.hw, "cfg_div_clk");
+	if (IS_ERR(clk))
+		return dev_err_ptr_probe(dev, PTR_ERR(clk),
+					 "Failed to get the cfg_div clock\n");
 
-	return 0;
+	return clk;
 }
 
 static int meson_mx_mmc_probe(struct platform_device *pdev)
@@ -682,16 +689,12 @@ static int meson_mx_mmc_probe(struct platform_device *pdev)
 		goto error_free_mmc;
 	}
 
-	host->parent_clk = devm_clk_get(host->controller_dev, "clkin");
-	if (IS_ERR(host->parent_clk)) {
-		ret = PTR_ERR(host->parent_clk);
+	host->cfg_div_clk = meson_mx_mmc_register_clk(&pdev->dev, base);
+	if (IS_ERR(host->cfg_div_clk)) {
+		ret = PTR_ERR(host->cfg_div_clk);
 		goto error_free_mmc;
 	}
 
-	ret = meson_mx_mmc_register_clks(host, base);
-	if (ret)
-		goto error_free_mmc;
-
 	ret = clk_prepare_enable(host->cfg_div_clk);
 	if (ret) {
 		dev_err(host->controller_dev, "Failed to enable MMC clock\n");