[PATCH 1/2] serial: sh-sci: HSCIF support

[Simon Horman <horms+renesas@verge.net.au>]

From: Ulrich Hecht <ulrich.hecht@gmail.com>

Adds support for "High Speed Serial Communications Interface with FIFO",
essentially a SCIF with 128-byte FIFOs and more accurate baud rate
generator.

Signed-off-by: Ulrich Hecht <ulrich.hecht@gmail.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
 drivers/tty/serial/sh-sci.c      |  102 +++++++++++++++++++++++++++++++++++---
 include/linux/serial_sci.h       |   12 +++--
 include/uapi/linux/serial_core.h |    3 ++
 3 files changed, 106 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 1564186..931d6c3 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -146,6 +146,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= sci_reg_invalid,
 		[SCLSR]		= sci_reg_invalid,
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -165,6 +166,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= sci_reg_invalid,
 		[SCLSR]		= sci_reg_invalid,
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -183,6 +185,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= sci_reg_invalid,
 		[SCLSR]		= sci_reg_invalid,
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -201,6 +204,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= { 0x3c, 16 },
 		[SCSPTR]	= sci_reg_invalid,
 		[SCLSR]		= sci_reg_invalid,
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -220,6 +224,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= { 0x20, 16 },
 		[SCLSR]		= { 0x24, 16 },
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -238,6 +243,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= sci_reg_invalid,
 		[SCLSR]		= sci_reg_invalid,
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -256,6 +262,26 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= { 0x20, 16 },
 		[SCLSR]		= { 0x24, 16 },
+		[HSSRR]		= sci_reg_invalid,
+	},
+
+	/*
+	 * Common HSCIF definitions.
+	 */
+	[SCIx_HSCIF_REGTYPE] = {
+		[SCSMR]		= { 0x00, 16 },
+		[SCBRR]		= { 0x04,  8 },
+		[SCSCR]		= { 0x08, 16 },
+		[SCxTDR]	= { 0x0c,  8 },
+		[SCxSR]		= { 0x10, 16 },
+		[SCxRDR]	= { 0x14,  8 },
+		[SCFCR]		= { 0x18, 16 },
+		[SCFDR]		= { 0x1c, 16 },
+		[SCTFDR]	= sci_reg_invalid,
+		[SCRFDR]	= sci_reg_invalid,
+		[SCSPTR]	= { 0x20, 16 },
+		[SCLSR]		= { 0x24, 16 },
+		[HSSRR]		= { 0x40, 16 },
 	},
 
 	/*
@@ -275,6 +301,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= sci_reg_invalid,
 		[SCLSR]		= { 0x24, 16 },
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -294,6 +321,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= { 0x20, 16 },
 		[SCSPTR]	= { 0x24, 16 },
 		[SCLSR]		= { 0x28, 16 },
+		[HSSRR]		= sci_reg_invalid,
 	},
 
 	/*
@@ -313,6 +341,7 @@ static struct plat_sci_reg sci_regmap[SCIx_NR_REGTYPES][SCIx_NR_REGS] = {
 		[SCRFDR]	= sci_reg_invalid,
 		[SCSPTR]	= sci_reg_invalid,
 		[SCLSR]		= sci_reg_invalid,
+		[HSSRR]		= sci_reg_invalid,
 	},
 };
 
@@ -374,6 +403,9 @@ static int sci_probe_regmap(struct plat_sci_port *cfg)
 		 */
 		cfg->regtype = SCIx_SH4_SCIF_REGTYPE;
 		break;
+	case PORT_HSCIF:
+		cfg->regtype = SCIx_HSCIF_REGTYPE;
+		break;
 	default:
 		printk(KERN_ERR "Can't probe register map for given port\n");
 		return -EINVAL;
@@ -1798,6 +1830,42 @@ static unsigned int sci_scbrr_calc(unsigned int algo_id, unsigned int bps,
 	return ((freq + 16 * bps) / (32 * bps) - 1);
 }
 
+/* calculate sample rate, BRR, and clock select for HSCIF */
+static void sci_baud_calc_hscif(unsigned int bps, unsigned long freq,
+				int *brr, unsigned int *srr,
+				unsigned int *cks)
+{
+	int sr, c, br, err;
+	int min_err = 1000; /* 100% */
+
+	/* Find the combination of sample rate and clock select with the
+	   smallest deviation from the desired baud rate. */
+	for (sr = 8; sr <= 32; sr++) {
+		for (c = 0; c <= 3; c++) {
+			/* integerized formulas from HSCIF documentation */
+			br = freq / (sr * (1 << (2 * c + 1)) * bps) - 1;
+			if (br < 0 || br > 255)
+				continue;
+			err = freq / ((br + 1) * bps * sr *
+			      (1 << (2 * c + 1)) / 1000) - 1000;
+			if (min_err > err) {
+				min_err = err;
+				*brr = br;
+				*srr = sr - 1;
+				*cks = c;
+			}
+		}
+	}
+
+	if (min_err = 1000) {
+		WARN_ON(1);
+		/* use defaults */
+		*brr = 255;
+		*srr = 15;
+		*cks = 0;
+	}
+}
+
 static void sci_reset(struct uart_port *port)
 {
 	struct plat_sci_reg *reg;
@@ -1821,6 +1889,7 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 	struct plat_sci_reg *reg;
 	unsigned int baud, smr_val, max_baud, cks;
 	int t = -1;
+	unsigned int srr;
 
 	/*
 	 * earlyprintk comes here early on with port->uartclk set to zero.
@@ -1833,8 +1902,17 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 	max_baud = port->uartclk ? port->uartclk / 16 : 115200;
 
 	baud = uart_get_baud_rate(port, termios, old, 0, max_baud);
-	if (likely(baud && port->uartclk))
-		t = sci_scbrr_calc(s->cfg->scbrr_algo_id, baud, port->uartclk);
+	if (likely(baud && port->uartclk)) {
+		if (s->cfg->scbrr_algo_id = SCBRR_ALGO_6) {
+			sci_baud_calc_hscif(baud, port->uartclk, &t, &srr,
+					    &cks);
+		} else {
+			t = sci_scbrr_calc(s->cfg->scbrr_algo_id, baud,
+					   port->uartclk);
+			for (cks = 0; t >= 256 && cks <= 3; cks++)
+				t >>= 2;
+		}
+	}
 
 	sci_port_enable(s);
 
@@ -1853,15 +1931,15 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	for (cks = 0; t >= 256 && cks <= 3; cks++)
-		t >>= 2;
-
 	dev_dbg(port->dev, "%s: SMR %x, cks %x, t %x, SCSCR %x\n",
 		__func__, smr_val, cks, t, s->cfg->scscr);
 
 	if (t >= 0) {
 		serial_port_out(port, SCSMR, (smr_val & ~3) | cks);
 		serial_port_out(port, SCBRR, t);
+		reg = sci_getreg(port, HSSRR);
+		if (reg->size)
+			serial_port_out(port, HSSRR, srr | HSCIF_SRE);
 		udelay((1000000+(baud-1)) / baud); /* Wait one bit interval */
 	} else
 		serial_port_out(port, SCSMR, smr_val);
@@ -1947,6 +2025,8 @@ static const char *sci_type(struct uart_port *port)
 		return "scifa";
 	case PORT_SCIFB:
 		return "scifb";
+	case PORT_HSCIF:
+		return "hscif";
 	}
 
 	return NULL;
@@ -1960,7 +2040,10 @@ static inline unsigned long sci_port_size(struct uart_port *port)
 	 * from platform resource data at such a time that ports begin to
 	 * behave more erratically.
 	 */
-	return 64;
+	if (port->type = PORT_HSCIF)
+		return 96;
+	else
+		return 64;
 }
 
 static int sci_remap_port(struct uart_port *port)
@@ -2085,6 +2168,9 @@ static int sci_init_single(struct platform_device *dev,
 	case PORT_SCIFB:
 		port->fifosize = 256;
 		break;
+	case PORT_HSCIF:
+		port->fifosize = 128;
+		break;
 	case PORT_SCIFA:
 		port->fifosize = 64;
 		break;
@@ -2325,7 +2411,7 @@ static inline int sci_probe_earlyprintk(struct platform_device *pdev)
 #endif /* CONFIG_SERIAL_SH_SCI_CONSOLE */
 
 static char banner[] __initdata -	KERN_INFO "SuperH SCI(F) driver initialized\n";
+	KERN_INFO "SuperH (H)SCI(F) driver initialized\n";
 
 static struct uart_driver sci_uart_driver = {
 	.owner		= THIS_MODULE,
@@ -2484,4 +2570,4 @@ module_exit(sci_exit);
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:sh-sci");
 MODULE_AUTHOR("Paul Mundt");
-MODULE_DESCRIPTION("SuperH SCI(F) serial driver");
+MODULE_DESCRIPTION("SuperH (H)SCI(F) serial driver");
diff --git a/include/linux/serial_sci.h b/include/linux/serial_sci.h
index eb763ad..d340497 100644
--- a/include/linux/serial_sci.h
+++ b/include/linux/serial_sci.h
@@ -5,7 +5,7 @@
 #include <linux/sh_dma.h>
 
 /*
- * Generic header for SuperH SCI(F) (used by sh/sh64/h8300 and related parts)
+ * Generic header for SuperH (H)SCI(F) (used by sh/sh64/h8300 and related parts)
  */
 
 #define SCIx_NOT_SUPPORTED	(-1)
@@ -16,6 +16,7 @@ enum {
 	SCBRR_ALGO_3,		/* (((clk * 2) + 16 * bps) / (16 * bps) - 1) */
 	SCBRR_ALGO_4,		/* (((clk * 2) + 16 * bps) / (32 * bps) - 1) */
 	SCBRR_ALGO_5,		/* (((clk * 1000 / 32) / bps) - 1) */
+	SCBRR_ALGO_6,		/* HSCIF variable sample rate algorithm */
 };
 
 #define SCSCR_TIE	(1 << 7)
@@ -37,7 +38,7 @@ enum {
 
 #define SCI_DEFAULT_ERROR_MASK (SCI_PER | SCI_FER)
 
-/* SCxSR SCIF */
+/* SCxSR SCIF, HSCIF */
 #define SCIF_ER    0x0080
 #define SCIF_TEND  0x0040
 #define SCIF_TDFE  0x0020
@@ -55,6 +56,9 @@ enum {
 #define SCSPTR_SPB2IO	(1 << 1)
 #define SCSPTR_SPB2DT	(1 << 0)
 
+/* HSSRR HSCIF */
+#define HSCIF_SRE	0x8000
+
 /* Offsets into the sci_port->irqs array */
 enum {
 	SCIx_ERI_IRQ,
@@ -90,6 +94,7 @@ enum {
 	SCIx_SH4_SCIF_NO_SCSPTR_REGTYPE,
 	SCIx_SH4_SCIF_FIFODATA_REGTYPE,
 	SCIx_SH7705_SCIF_REGTYPE,
+	SCIx_HSCIF_REGTYPE,
 
 	SCIx_NR_REGTYPES,
 };
@@ -115,6 +120,7 @@ enum {
 	SCSMR, SCBRR, SCSCR, SCxSR,
 	SCFCR, SCFDR, SCxTDR, SCxRDR,
 	SCLSR, SCTFDR, SCRFDR, SCSPTR,
+	HSSRR,
 
 	SCIx_NR_REGS,
 };
@@ -137,7 +143,7 @@ struct plat_sci_port {
 	unsigned long	mapbase;		/* resource base */
 	unsigned int	irqs[SCIx_NR_IRQS];	/* ERI, RXI, TXI, BRI */
 	unsigned int	gpios[SCIx_NR_FNS];	/* SCK, RXD, TXD, CTS, RTS */
-	unsigned int	type;			/* SCI / SCIF / IRDA */
+	unsigned int	type;			/* SCI / SCIF / IRDA / HSCIF */
 	upf_t		flags;			/* UPF_* flags */
 	unsigned long	capabilities;		/* Port features/capabilities */
 
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 74c2bf7..26eee07 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -226,4 +226,7 @@
 /* Rocketport EXPRESS/INFINITY */
 #define PORT_RP2	102
 
+/* SH-SCI */
+#define PORT_HSCIF	103
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */
-- 
1.7.10.4