MIPS: ath25: add basic AR5312 SoC support

Add basic support for Atheros AR5312/AR2312 SoCs: registers definition
file and initial setup code.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: Linux MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/8238/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 155 insertions, 0 deletions

diff --git a/arch/mips/ath25/ar5312.c b/arch/mips/ath25/ar5312.c
new file mode 100644
index 000000000000..c2adaf2cd73a
--- /dev/null
+++ b/arch/mips/ath25/ar5312.c
@@ -0,0 +1,155 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2003 Atheros Communications, Inc.,  All Rights Reserved.
+ * Copyright (C) 2006 FON Technology, SL.
+ * Copyright (C) 2006 Imre Kaloz <kaloz@openwrt.org>
+ * Copyright (C) 2006-2009 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2012 Alexandros C. Couloumbis <alex@ozo.com>
+ */
+
+/*
+ * Platform devices for Atheros AR5312 SoCs
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/reboot.h>
+#include <asm/bootinfo.h>
+#include <asm/reboot.h>
+#include <asm/time.h>
+
+#include "devices.h"
+#include "ar5312.h"
+#include "ar5312_regs.h"
+
+static void __iomem *ar5312_rst_base;
+
+static inline u32 ar5312_rst_reg_read(u32 reg)
+{
+	return __raw_readl(ar5312_rst_base + reg);
+}
+
+static inline void ar5312_rst_reg_write(u32 reg, u32 val)
+{
+	__raw_writel(val, ar5312_rst_base + reg);
+}
+
+static inline void ar5312_rst_reg_mask(u32 reg, u32 mask, u32 val)
+{
+	u32 ret = ar5312_rst_reg_read(reg);
+
+	ret &= ~mask;
+	ret |= val;
+	ar5312_rst_reg_write(reg, ret);
+}
+
+static void ar5312_restart(char *command)
+{
+	/* reset the system */
+	local_irq_disable();
+	while (1)
+		ar5312_rst_reg_write(AR5312_RESET, AR5312_RESET_SYSTEM);
+}
+
+/*
+ * This table is indexed by bits 5..4 of the CLOCKCTL1 register
+ * to determine the predevisor value.
+ */
+static unsigned clockctl1_predivide_table[4] __initdata = { 1, 2, 4, 5 };
+
+static unsigned __init ar5312_cpu_frequency(void)
+{
+	u32 scratch, devid, clock_ctl1;
+	u32 predivide_mask, multiplier_mask, doubler_mask;
+	unsigned predivide_shift, multiplier_shift;
+	unsigned predivide_select, predivisor, multiplier;
+
+	/* Trust the bootrom's idea of cpu frequency. */
+	scratch = ar5312_rst_reg_read(AR5312_SCRATCH);
+	if (scratch)
+		return scratch;
+
+	devid = ar5312_rst_reg_read(AR5312_REV);
+	devid = (devid & AR5312_REV_MAJ) >> AR5312_REV_MAJ_S;
+	if (devid == AR5312_REV_MAJ_AR2313) {
+		predivide_mask = AR2313_CLOCKCTL1_PREDIVIDE_MASK;
+		predivide_shift = AR2313_CLOCKCTL1_PREDIVIDE_SHIFT;
+		multiplier_mask = AR2313_CLOCKCTL1_MULTIPLIER_MASK;
+		multiplier_shift = AR2313_CLOCKCTL1_MULTIPLIER_SHIFT;
+		doubler_mask = AR2313_CLOCKCTL1_DOUBLER_MASK;
+	} else { /* AR5312 and AR2312 */
+		predivide_mask = AR5312_CLOCKCTL1_PREDIVIDE_MASK;
+		predivide_shift = AR5312_CLOCKCTL1_PREDIVIDE_SHIFT;
+		multiplier_mask = AR5312_CLOCKCTL1_MULTIPLIER_MASK;
+		multiplier_shift = AR5312_CLOCKCTL1_MULTIPLIER_SHIFT;
+		doubler_mask = AR5312_CLOCKCTL1_DOUBLER_MASK;
+	}
+
+	/*
+	 * Clocking is derived from a fixed 40MHz input clock.
+	 *
+	 *  cpu_freq = input_clock * MULT (where MULT is PLL multiplier)
+	 *  sys_freq = cpu_freq / 4	  (used for APB clock, serial,
+	 *				   flash, Timer, Watchdog Timer)
+	 *
+	 *  cnt_freq = cpu_freq / 2	  (use for CPU count/compare)
+	 *
+	 * So, for example, with a PLL multiplier of 5, we have
+	 *
+	 *  cpu_freq = 200MHz
+	 *  sys_freq = 50MHz
+	 *  cnt_freq = 100MHz
+	 *
+	 * We compute the CPU frequency, based on PLL settings.
+	 */
+
+	clock_ctl1 = ar5312_rst_reg_read(AR5312_CLOCKCTL1);
+	predivide_select = (clock_ctl1 & predivide_mask) >> predivide_shift;
+	predivisor = clockctl1_predivide_table[predivide_select];
+	multiplier = (clock_ctl1 & multiplier_mask) >> multiplier_shift;
+
+	if (clock_ctl1 & doubler_mask)
+		multiplier <<= 1;
+
+	return (40000000 / predivisor) * multiplier;
+}
+
+static inline unsigned ar5312_sys_frequency(void)
+{
+	return ar5312_cpu_frequency() / 4;
+}
+
+void __init ar5312_plat_time_init(void)
+{
+	mips_hpt_frequency = ar5312_cpu_frequency() / 2;
+}
+
+void __init ar5312_plat_mem_setup(void)
+{
+	void __iomem *sdram_base;
+	u32 memsize, memcfg, bank0_ac, bank1_ac;
+
+	/* Detect memory size */
+	sdram_base = ioremap_nocache(AR5312_SDRAMCTL_BASE,
+				     AR5312_SDRAMCTL_SIZE);
+	memcfg = __raw_readl(sdram_base + AR5312_MEM_CFG1);
+	bank0_ac = ATH25_REG_MS(memcfg, AR5312_MEM_CFG1_AC0);
+	bank1_ac = ATH25_REG_MS(memcfg, AR5312_MEM_CFG1_AC1);
+	memsize = (bank0_ac ? (1 << (bank0_ac + 1)) : 0) +
+		  (bank1_ac ? (1 << (bank1_ac + 1)) : 0);
+	memsize <<= 20;
+	add_memory_region(0, memsize, BOOT_MEM_RAM);
+	iounmap(sdram_base);
+
+	ar5312_rst_base = ioremap_nocache(AR5312_RST_BASE, AR5312_RST_SIZE);
+
+	/* Clear any lingering AHB errors */
+	ar5312_rst_reg_read(AR5312_PROCADDR);
+	ar5312_rst_reg_read(AR5312_DMAADDR);
+	ar5312_rst_reg_write(AR5312_WDT_CTRL, AR5312_WDT_CTRL_IGNORE);
+
+	_machine_restart = ar5312_restart;
+}