Convert the sun7i-gmac driver to use a regmap-based driver,
instead of relying on the custom clock implementation.

This allows to get rid of the last custom clock in the sun7i
device tree making the sun7i fully CCU-compatible.

Compatibility with existing devicetrees is retained.

Signed-off-by: Priit Laes <pl...@plaes.org>
---
 .../net/ethernet/stmicro/stmmac/dwmac-sunxi.c | 130 ++++++++++++++++--
 1 file changed, 122 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c 
b/drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c
index 0e1ca2cba3c7..206398f7a2af 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sunxi.c
@@ -12,8 +12,11 @@
 #include <linux/module.h>
 #include <linux/phy.h>
 #include <linux/platform_device.h>
+#include <linux/of_device.h>
 #include <linux/of_net.h>
 #include <linux/regulator/consumer.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
 
 #include "stmmac_platform.h"
 
@@ -22,11 +25,23 @@ struct sunxi_priv_data {
        int clk_enabled;
        struct clk *tx_clk;
        struct regulator *regulator;
+       struct regmap_field *regmap_field;
+};
+
+/* EMAC clock register @ 0x164 in the CCU address range */
+static const struct reg_field ccu_reg_field = {
+       .reg = 0x164,
+       .lsb = 0,
+       .msb = 31,
 };
 
 #define SUN7I_GMAC_GMII_RGMII_RATE     125000000
 #define SUN7I_GMAC_MII_RATE            25000000
 
+#define SUN7I_A20_CLK_MASK             GENMASK(2, 0)
+#define SUN7I_A20_RGMII_CLK            (BIT(2) | BIT(1))
+#define SUN7I_A20_MII_CLK              0
+
 static int sun7i_gmac_init(struct platform_device *pdev, void *priv)
 {
        struct sunxi_priv_data *gmac = priv;
@@ -38,7 +53,20 @@ static int sun7i_gmac_init(struct platform_device *pdev, 
void *priv)
                        return ret;
        }
 
-       /* Set GMAC interface port mode
+       if (gmac->regmap_field) {
+               if (phy_interface_mode_is_rgmii(gmac->interface)) {
+                       regmap_field_update_bits(gmac->regmap_field,
+                                                SUN7I_A20_CLK_MASK,
+                                                SUN7I_A20_RGMII_CLK);
+                       return clk_prepare_enable(gmac->tx_clk);
+               }
+               regmap_field_update_bits(gmac->regmap_field,
+                                        SUN7I_A20_CLK_MASK,
+                                        SUN7I_A20_MII_CLK);
+               return clk_enable(gmac->tx_clk);
+       }
+
+       /* Legacy devicetree clock (allwinner,sun7i-a20-gmac-clk) support:
         *
         * The GMAC TX clock lines are configured by setting the clock
         * rate, which then uses the auto-reparenting feature of the
@@ -62,9 +90,16 @@ static void sun7i_gmac_exit(struct platform_device *pdev, 
void *priv)
 {
        struct sunxi_priv_data *gmac = priv;
 
-       if (gmac->clk_enabled) {
+       if (gmac->regmap_field) {
+               regmap_field_update_bits(gmac->regmap_field,
+                                        SUN7I_A20_CLK_MASK, 0);
                clk_disable(gmac->tx_clk);
-               gmac->clk_enabled = 0;
+       } else {
+               /* Handle legacy devicetree clock (sun7i-a20-gmac-clk) */
+               if (gmac->clk_enabled) {
+                       clk_disable(gmac->tx_clk);
+                       gmac->clk_enabled = 0;
+               }
        }
        clk_unprepare(gmac->tx_clk);
 
@@ -72,10 +107,55 @@ static void sun7i_gmac_exit(struct platform_device *pdev, 
void *priv)
                regulator_disable(gmac->regulator);
 }
 
+static struct regmap *sun7i_gmac_get_syscon_from_dev(struct device_node *node)
+{
+       struct device_node *syscon_node;
+       struct platform_device *syscon_pdev;
+       struct regmap *regmap = NULL;
+
+       syscon_node = of_parse_phandle(node, "syscon", 0);
+       if (!syscon_node)
+               return ERR_PTR(-ENODEV);
+
+       syscon_pdev = of_find_device_by_node(syscon_node);
+       if (!syscon_pdev) {
+               /* platform device might not be probed yet */
+               regmap = ERR_PTR(-EPROBE_DEFER);
+               goto out_put_node;
+       }
+
+       /* If no regmap is found then the other device driver is at fault */
+       regmap = dev_get_regmap(&syscon_pdev->dev, NULL);
+       if (!regmap)
+               regmap = ERR_PTR(-EINVAL);
+
+       platform_device_put(syscon_pdev);
+out_put_node:
+       of_node_put(syscon_node);
+       return regmap;
+}
+
 static void sun7i_fix_speed(void *priv, unsigned int speed)
 {
        struct sunxi_priv_data *gmac = priv;
 
+       if (gmac->regmap_field) {
+               clk_disable(gmac->tx_clk);
+               clk_unprepare(gmac->tx_clk);
+               if (speed == 1000)
+                       regmap_field_update_bits(gmac->regmap_field,
+                                                SUN7I_A20_CLK_MASK,
+                                                SUN7I_A20_RGMII_CLK);
+               else
+                       regmap_field_update_bits(gmac->regmap_field,
+                                                SUN7I_A20_CLK_MASK,
+                                                SUN7I_A20_MII_CLK);
+               clk_prepare_enable(gmac->tx_clk);
+               return;
+       }
+
+       /* Handle legacy devicetree clock (sun7i-a20-gmac-clk) */
+
        /* only GMII mode requires us to reconfigure the clock lines */
        if (gmac->interface != PHY_INTERFACE_MODE_GMII)
                return;
@@ -102,6 +182,8 @@ static int sun7i_gmac_probe(struct platform_device *pdev)
        struct stmmac_resources stmmac_res;
        struct sunxi_priv_data *gmac;
        struct device *dev = &pdev->dev;
+       struct device_node *syscon_node;
+       struct regmap *regmap = NULL;
        int ret;
 
        ret = stmmac_get_platform_resources(pdev, &stmmac_res);
@@ -124,11 +206,43 @@ static int sun7i_gmac_probe(struct platform_device *pdev)
                goto err_remove_config_dt;
        }
 
-       gmac->tx_clk = devm_clk_get(dev, "allwinner_gmac_tx");
-       if (IS_ERR(gmac->tx_clk)) {
-               dev_err(dev, "could not get tx clock\n");
-               ret = PTR_ERR(gmac->tx_clk);
-               goto err_remove_config_dt;
+       /* Attempt to fetch syscon node... */
+       syscon_node = of_parse_phandle(dev->of_node, "syscon", 0);
+       if (syscon_node) {
+               gmac->tx_clk = devm_clk_get(dev, "stmmaceth");
+               if (IS_ERR(gmac->tx_clk)) {
+                       dev_err(dev, "Could not get TX clock\n");
+                       ret = PTR_ERR(gmac->tx_clk);
+                       goto err_remove_config_dt;
+               }
+
+               regmap = sun7i_gmac_get_syscon_from_dev(pdev->dev.of_node);
+               if (IS_ERR(regmap))
+                       regmap = 
syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+                                                                "syscon");
+               if (IS_ERR(regmap)) {
+                       ret = PTR_ERR(regmap);
+                       dev_err(&pdev->dev, "Unable to map syscon: %d\n", ret);
+                       goto err_remove_config_dt;
+               }
+
+               gmac->regmap_field = devm_regmap_field_alloc(dev, regmap,
+                                                            ccu_reg_field);
+
+               if (IS_ERR(gmac->regmap_field)) {
+                       ret = PTR_ERR(gmac->regmap_field);
+                       dev_err(dev, "Unable to map syscon register: %d\n", 
ret);
+                       goto err_remove_config_dt;
+               }
+       /* ...or fall back to legacy clock setup */
+       } else {
+               gmac->tx_clk = devm_clk_get(dev, "allwinner_gmac_tx");
+               if (IS_ERR(gmac->tx_clk)) {
+                       dev_err(dev, "could not get tx clock\n");
+                       ret = PTR_ERR(gmac->tx_clk);
+                       goto err_remove_config_dt;
+               }
+               dev_info(dev, "allwinner_gmac_tx support is deprecated!\n");
        }
 
        /* Optional regulator for PHY */
-- 
2.26.2

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