stmmac: dwmac-sti: review the glue-logic for STi4xx and STiD127 SoCs

This patch is to review the whole glue logic adopted on STi SoCs that
was bugged.

In the old glue-logic there was a lot of confusion when setup the
retiming especially for STiD127 where, for example, the bits 6 and 7
(in the GMAC  control register) have a different meaning of what is
used for STiH4xx SoCs. So we cannot adopt the same glue for all these
SoCs.
Moreover, GiGa on STiD127 didn't work and, for all the SoCs, the RGMII
couldn't run when the speed was 10Mbps (because the clock was not properly
managed).
Note that the phy clock needs to be provided by the platform as well as
documented in the related binding file (updated as consequence).

The old code supported too many configurations never adopted and validated.
This made the code very complex to maintain and debug in case of issues.

The patch simplifies all the configurations as commented in the tables
inside the file and obviously it has been tested on all the boards
based on the SoCs mentioned.

With this patch, the dwmac-sti is also ready to support new configurations that
will be available on next SoC generations.
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/sti-dwmac.txt

 STMicroelectronics SoC DWMAC glue layer controller
 
+This file documents differences between the core properties in
+Documentation/devicetree/bindings/net/stmmac.txt
+and what is needed on STi platforms to program the stmmac glue logic.
+
 The device node has following properties.
 
 Required properties:
  - compatible	: Can be "st,stih415-dwmac", "st,stih416-dwmac",
-   "st,stid127-dwmac", "st,stih407-dwmac".
- - reg		: Offset of the glue configuration register map in system
+   "st,stih407-dwmac", "st,stid127-dwmac".
+ - reg : Offset of the glue configuration register map in system
    configuration regmap pointed by st,syscon property and size.
-
- - reg-names	: Should be "sti-ethconf".
-
- - st,syscon	: Should be phandle to system configuration node which
+ - st,syscon : Should be phandle to system configuration node which
    encompases this glue registers.
+ - st,gmac_en: this is to enable the gmac into a dedicated sysctl control
+   register available on STiH407 SoC.
+ - sti-ethconf: this is the gmac glue logic register to enable the GMAC,
+   select among the different modes and program the clk retiming.
+ - pinctrl-0: pin-control for all the MII mode supported.
 
- - st,tx-retime-src: On STi Parts for Giga bit speeds, 125Mhz clocks can be
-   wired up in from different sources. One via TXCLK pin and other via CLK_125
-   pin. This wiring is totally board dependent. However the retiming glue
-   logic should be configured accordingly. Possible values for this property
-
-	   "txclk" - if 125Mhz clock is wired up via txclk line.
-	   "clk_125" - if 125Mhz clock is wired up via clk_125 line.
-
-   This property is only valid for Giga bit setup( GMII, RGMII), and it is
-   un-used for non-giga bit (MII and RMII) setups. Also note that internal
-   clockgen can not generate stable 125Mhz clock.
-
- - st,ext-phyclk: This boolean property indicates who is generating the clock
-  for tx and rx. This property is only valid for RMII case where the clock can
-  be generated from the MAC or PHY.
-
- - clock-names: should be "sti-ethclk".
- - clocks: Should point to ethernet clockgen which can generate phyclk.
-
+Optional properties:
+ - resets : phandle pointing to the system reset controller with correct
+   reset line index for ethernet reset.
+ - st,ext-phyclk: valid only for RMII where PHY can generate 50MHz clock or
+   MAC can generate it.
+ - st,tx-retime-src: This specifies which clk is wired up to the mac for
+   retimeing tx lines. This is totally board dependent and can take one of the
+   posssible values from "txclk", "clk_125" or "clkgen".
+   If not passed, the internal clock will be used by default.
+ - sti-ethclk: this is the phy clock.
+ - sti-clkconf: this is an extra sysconfig register, available in new SoCs,
+   to program the clk retiming.
+ - st,gmac_en: to enable the GMAC, this only is present in some SoCs; e.g.
+   STiH407.
 
 Example:
 
-ethernet0: dwmac@fe810000 {
-	device_type 	= "network";
-	compatible	= "st,stih416-dwmac", "snps,dwmac", "snps,dwmac-3.710";
-	reg 		= <0xfe810000 0x8000>, <0x8bc 0x4>;
-	reg-names	= "stmmaceth", "sti-ethconf";
-	interrupts	= <0 133 0>, <0 134 0>, <0 135 0>;
-	interrupt-names	= "macirq", "eth_wake_irq", "eth_lpi";
-	phy-mode	= "mii";
+ethernet0: dwmac@9630000 {
+	device_type = "network";
+	status = "disabled";
+	compatible = "st,stih407-dwmac", "snps,dwmac", "snps,dwmac-3.710";
+	reg = <0x9630000 0x8000>, <0x80 0x4>;
+	reg-names = "stmmaceth", "sti-ethconf";
 
-	st,syscon	= <&syscfg_rear>;
+	st,syscon = <&syscfg_sbc_reg>;
+	st,gmac_en;
+	resets = <&softreset STIH407_ETH1_SOFTRESET>;
+	reset-names = "stmmaceth";
 
-	snps,pbl 	= <32>;
+	interrupts = <GIC_SPI 98 IRQ_TYPE_NONE>,
+		     <GIC_SPI 99 IRQ_TYPE_NONE>,
+		     <GIC_SPI 100 IRQ_TYPE_NONE>;
+	interrupt-names = "macirq", "eth_wake_irq", "eth_lpi";
+
+	snps,pbl = <32>;
 	snps,mixed-burst;
 
-	resets		= <&softreset STIH416_ETH0_SOFTRESET>;
-	reset-names	= "stmmaceth";
-	pinctrl-0	= <&pinctrl_mii0>;
-	pinctrl-names 	= "default";
-	clocks		= <&CLK_S_GMAC0_PHY>;
-	clock-names	= "stmmaceth";
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_rgmii1>;
+
+	clock-names = "stmmaceth", "sti-ethclk";
+	clocks = <&CLK_S_C0_FLEXGEN CLK_EXT2F_A9>,
+		 <&CLK_S_C0_FLEXGEN CLK_ETH_PHY>;
 };