pepper: Implement Board Detection mechanism

AM335x-based 'Gumstix Pepper' SBCs and variants use different types of
RAM (DDR2 vs DDR3 with DDR3 being the default).  Detect the board type
by reading the factory-programmed EEPROM [1] and use this to select any
runtime boot options such as RAM type.

[1] http://elinux.org/BeagleBoardPinMux#List_of_Vendor_and_Device_IDs

Signed-off-by: Adam YH Lee <adam.yh.lee@gmail.com>
Signed-off-by: Ash Charles <ashcharles@gmail.com>

board/gumstix/pepper/board.c

@@ -33,6 +33,46 @@
 DECLARE_GLOBAL_DATA_PTR;
 
 #ifdef CONFIG_SPL_BUILD
+#define OSC	(V_OSCK/1000000)
+
+static const struct ddr_data ddr3_data = {
+	.datardsratio0 = MT41K256M16HA125E_RD_DQS,
+	.datawdsratio0 = MT41K256M16HA125E_WR_DQS,
+	.datafwsratio0 = MT41K256M16HA125E_PHY_FIFO_WE,
+	.datawrsratio0 = MT41K256M16HA125E_PHY_WR_DATA,
+};
+
+static const struct cmd_control ddr3_cmd_ctrl_data = {
+	.cmd0csratio = MT41K256M16HA125E_RATIO,
+	.cmd0iclkout = MT41K256M16HA125E_INVERT_CLKOUT,
+
+	.cmd1csratio = MT41K256M16HA125E_RATIO,
+	.cmd1iclkout = MT41K256M16HA125E_INVERT_CLKOUT,
+
+	.cmd2csratio = MT41K256M16HA125E_RATIO,
+	.cmd2iclkout = MT41K256M16HA125E_INVERT_CLKOUT,
+};
+
+static struct emif_regs ddr3_emif_reg_data = {
+	.sdram_config = MT41K256M16HA125E_EMIF_SDCFG,
+	.ref_ctrl = MT41K256M16HA125E_EMIF_SDREF,
+	.sdram_tim1 = MT41K256M16HA125E_EMIF_TIM1,
+	.sdram_tim2 = MT41K256M16HA125E_EMIF_TIM2,
+	.sdram_tim3 = MT41K256M16HA125E_EMIF_TIM3,
+	.zq_config = MT41K256M16HA125E_ZQ_CFG,
+	.emif_ddr_phy_ctlr_1 = MT41K256M16HA125E_EMIF_READ_LATENCY,
+};
+
+const struct dpll_params dpll_ddr3 = {400, OSC-1, 1, -1, -1, -1, -1};
+
+const struct ctrl_ioregs ioregs_ddr3 = {
+	.cm0ioctl               = MT41K256M16HA125E_IOCTRL_VALUE,
+	.cm1ioctl               = MT41K256M16HA125E_IOCTRL_VALUE,
+	.cm2ioctl               = MT41K256M16HA125E_IOCTRL_VALUE,
+	.dt0ioctl               = MT41K256M16HA125E_IOCTRL_VALUE,
+	.dt1ioctl               = MT41K256M16HA125E_IOCTRL_VALUE,
+};
+
 static const struct ddr_data ddr2_data = {
 	.datardsratio0 = MT47H128M16RT25E_RD_DQS,
 	.datafwsratio0 = MT47H128M16RT25E_PHY_FIFO_WE,
@@ -56,6 +96,70 @@ static const struct emif_regs ddr2_emif_reg_data = {
 	.emif_ddr_phy_ctlr_1 = MT47H128M16RT25E_EMIF_READ_LATENCY,
 };
 
+const struct dpll_params dpll_ddr2 = {266, OSC-1, 1, -1, -1, -1, -1};
+
+const struct ctrl_ioregs ioregs_ddr2 = {
+	.cm0ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
+	.cm1ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
+	.cm2ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
+	.dt0ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
+	.dt1ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
+};
+
+static int read_eeprom(struct pepper_board_id *header)
+{
+	if (i2c_probe(CONFIG_SYS_I2C_EEPROM_ADDR)) {
+		return -ENODEV;
+	}
+
+	if (i2c_read(CONFIG_SYS_I2C_EEPROM_ADDR, 0, 1, (uchar *)header,
+		sizeof(struct pepper_board_id))) {
+		return -EIO;
+	}
+
+	return 0;
+}
+
+const struct dpll_params *get_dpll_ddr_params(void)
+{
+	struct pepper_board_id header;
+
+	enable_i2c0_pin_mux();
+	i2c_set_bus_num(0);
+
+	if (read_eeprom(&header) < 0)
+		return &dpll_ddr3;
+
+	switch (header.device_vendor) {
+	case GUMSTIX_PEPPER:
+		return &dpll_ddr2;
+	case GUMSTIX_PEPPER_DVI:
+		return &dpll_ddr3;
+	default:
+		return &dpll_ddr3;
+	}
+}
+
+void sdram_init(void)
+{
+	const struct dpll_params *dpll = get_dpll_ddr_params();
+
+	/*
+	 * Here we are assuming PLL clock reveals the type of RAM.
+	 * DDR2 = 266
+	 * DDR3 = 400
+	 * Note that DDR3 is the default.
+	 */
+	if (dpll->m == 266) {
+		config_ddr(dpll->m, &ioregs_ddr2, &ddr2_data,
+			&ddr2_cmd_ctrl_data, &ddr2_emif_reg_data, 0);
+	}
+	else if (dpll->m == 400) {
+		config_ddr(dpll->m, &ioregs_ddr3, &ddr3_data,
+			&ddr3_cmd_ctrl_data, &ddr3_emif_reg_data, 0);
+	}
+}
+
 #ifdef CONFIG_SPL_OS_BOOT
 int spl_start_uboot(void)
 {
@@ -64,14 +168,6 @@ int spl_start_uboot(void)
 }
 #endif
 
-#define OSC	(V_OSCK/1000000)
-const struct dpll_params dpll_ddr = {266, OSC-1, 1, -1, -1, -1, -1};
-
-const struct dpll_params *get_dpll_ddr_params(void)
-{
-	return &dpll_ddr;
-}
-
 void set_uart_mux_conf(void)
 {
 	enable_uart0_pin_mux();
@@ -82,19 +178,7 @@ void set_mux_conf_regs(void)
 	enable_board_pin_mux();
 }
 
-const struct ctrl_ioregs ioregs = {
-	.cm0ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
-	.cm1ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
-	.cm2ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
-	.dt0ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
-	.dt1ioctl		= MT47H128M16RT25E_IOCTRL_VALUE,
-};
 
-void sdram_init(void)
-{
-	config_ddr(266, &ioregs, &ddr2_data,
-		   &ddr2_cmd_ctrl_data, &ddr2_emif_reg_data, 0);
-}
 #endif
 
 int board_init(void)

board/gumstix/pepper/board.h

@@ -9,6 +9,18 @@
 #ifndef _BOARD_H_
 #define _BOARD_H_
 
+#define GUMSTIX_PEPPER		0x30000200
+#define GUMSTIX_PEPPER_DVI	0x31000200
+
+struct pepper_board_id {
+	unsigned int device_vendor;
+	unsigned char revision;
+	unsigned char content;
+	char fab_revision[8];
+	char env_var[16];
+	char en_setting[64];
+};
+
 /*
  * We must be able to enable uart0, for initial output. We then have a
  * main pinmux function that can be overridden to enable all other pinmux that
@@ -16,4 +28,5 @@
  */
 void enable_uart0_pin_mux(void);
 void enable_board_pin_mux(void);
+void enable_i2c0_pin_mux(void);
 #endif

board/gumstix/pepper/mux.c

@@ -64,6 +64,11 @@ void enable_uart0_pin_mux(void)
 	configure_module_pin_mux(uart0_pin_mux);
 }
 
+void enable_i2c0_pin_mux(void)
+{
+	configure_module_pin_mux(i2c0_pin_mux);
+}
+
 /*
  * Do board-specific muxes.
  */

include/configs/pepper.h

@@ -20,6 +20,8 @@
 #undef CONFIG_SYS_PROMPT
 #define CONFIG_SYS_PROMPT		"pepper# "
 
+#define CONFIG_SYS_I2C_EEPROM_ADDR	0x50
+
 /* Mach type */
 #define MACH_TYPE_PEPPER		4207	/* Until the next sync */
 #define CONFIG_MACH_TYPE		MACH_TYPE_PEPPER