mfd: syscon: atmel-smc: Add new helpers to ease SMC regs manipulation

Add helper functions for atmel Static Memory Controller. The functions
are required to configure SMC. This file is inherited from the work
done by Boris Brezillon for Linux

Signed-off-by: Balamanikandan Gunasundar <balamanikandan.gunasundar@microchip.com>

3 files changed, 369 insertions, 0 deletions

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
new file mode 100644
index 0000000000..ae53b02f27
--- /dev/null
+++ b/drivers/mfd/Kconfig
@@ -0,0 +1,4 @@
+config MFD_ATMEL_SMC
+       bool "Atmel Static Memory Controller driver"
+       help
+	Say yes here to support Atmel Static Memory Controller driver.
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
new file mode 100644
index 0000000000..4454815a98
--- /dev/null
+++ b/drivers/mfd/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_MFD_ATMEL_SMC) += atmel-smc.o
diff --git a/drivers/mfd/atmel-smc.c b/drivers/mfd/atmel-smc.c
new file mode 100644
index 0000000000..15296f71a1
--- /dev/null
+++ b/drivers/mfd/atmel-smc.c
@@ -0,0 +1,364 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Atmel SMC (Static Memory Controller) helper functions.
+ *
+ * Copyright (C) 2022 Microchip Technology Inc.
+ * Copyright (C) 2017 Free Electrons
+ *
+ * Author: Boris Brezillon <boris.brezillon@free-electrons.com>
+ */
+
+#include <clk.h>
+#include <dm/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/mfd/syscon/atmel-smc.h>
+#include <linux/string.h>
+
+/**
+ * atmel_smc_cs_conf_init - initialize a SMC CS conf
+ * @conf: the SMC CS conf to initialize
+ *
+ * Set all fields to 0 so that one can start defining a new config.
+ */
+void atmel_smc_cs_conf_init(struct atmel_smc_cs_conf *conf)
+{
+	memset(conf, 0, sizeof(*conf));
+}
+EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_init);
+
+/**
+ * atmel_smc_cs_encode_ncycles - encode a number of MCK clk cycles in the
+ *				 format expected by the SMC engine
+ * @ncycles: number of MCK clk cycles
+ * @msbpos: position of the MSB part of the timing field
+ * @msbwidth: width of the MSB part of the timing field
+ * @msbfactor: factor applied to the MSB
+ * @encodedval: param used to store the encoding result
+ *
+ * This function encodes the @ncycles value as described in the datasheet
+ * (section "SMC Setup/Pulse/Cycle/Timings Register"). This is a generic
+ * helper which called with different parameter depending on the encoding
+ * scheme.
+ *
+ * If the @ncycles value is too big to be encoded, -ERANGE is returned and
+ * the encodedval is contains the maximum val. Otherwise, 0 is returned.
+ */
+static int atmel_smc_cs_encode_ncycles(unsigned int ncycles,
+				       unsigned int msbpos,
+				       unsigned int msbwidth,
+				       unsigned int msbfactor,
+				       unsigned int *encodedval)
+{
+	unsigned int lsbmask = GENMASK(msbpos - 1, 0);
+	unsigned int msbmask = GENMASK(msbwidth - 1, 0);
+	unsigned int msb, lsb;
+	int ret = 0;
+
+	msb = ncycles / msbfactor;
+	lsb = ncycles % msbfactor;
+
+	if (lsb > lsbmask) {
+		lsb = 0;
+		msb++;
+	}
+
+	/*
+	 * Let's just put the maximum we can if the requested setting does
+	 * not fit in the register field.
+	 * We still return -ERANGE in case the caller cares.
+	 */
+	if (msb > msbmask) {
+		msb = msbmask;
+		lsb = lsbmask;
+		ret = -ERANGE;
+	}
+
+	*encodedval = (msb << msbpos) | lsb;
+
+	return ret;
+}
+
+/**
+ * atmel_smc_cs_conf_set_timing - set the SMC CS conf Txx parameter to a
+ *				  specific value
+ * @conf: SMC CS conf descriptor
+ * @shift: the position of the Txx field in the TIMINGS register
+ * @ncycles: value (expressed in MCK clk cycles) to assign to this Txx
+ *	     parameter
+ *
+ * This function encodes the @ncycles value as described in the datasheet
+ * (section "SMC Timings Register"), and then stores the result in the
+ * @conf->timings field at @shift position.
+ *
+ * Returns -EINVAL if shift is invalid, -ERANGE if ncycles does not fit in
+ * the field, and 0 otherwise.
+ */
+int atmel_smc_cs_conf_set_timing(struct atmel_smc_cs_conf *conf,
+				 unsigned int shift, unsigned int ncycles)
+{
+	unsigned int val;
+	int ret;
+
+	if (shift != ATMEL_HSMC_TIMINGS_TCLR_SHIFT &&
+	    shift != ATMEL_HSMC_TIMINGS_TADL_SHIFT &&
+	    shift != ATMEL_HSMC_TIMINGS_TAR_SHIFT &&
+	    shift != ATMEL_HSMC_TIMINGS_TRR_SHIFT &&
+	    shift != ATMEL_HSMC_TIMINGS_TWB_SHIFT)
+		return -EINVAL;
+
+	/*
+	 * The formula described in atmel datasheets (section "HSMC Timings
+	 * Register"):
+	 *
+	 * ncycles = (Txx[3] * 64) + Txx[2:0]
+	 */
+	ret = atmel_smc_cs_encode_ncycles(ncycles, 3, 1, 64, &val);
+	conf->timings &= ~GENMASK(shift + 3, shift);
+	conf->timings |= val << shift;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_set_timing);
+
+/**
+ * atmel_smc_cs_conf_set_setup - set the SMC CS conf xx_SETUP parameter to a
+ *				 specific value
+ * @conf: SMC CS conf descriptor
+ * @shift: the position of the xx_SETUP field in the SETUP register
+ * @ncycles: value (expressed in MCK clk cycles) to assign to this xx_SETUP
+ *	     parameter
+ *
+ * This function encodes the @ncycles value as described in the datasheet
+ * (section "SMC Setup Register"), and then stores the result in the
+ * @conf->setup field at @shift position.
+ *
+ * Returns -EINVAL if @shift is invalid, -ERANGE if @ncycles does not fit in
+ * the field, and 0 otherwise.
+ */
+int atmel_smc_cs_conf_set_setup(struct atmel_smc_cs_conf *conf,
+				unsigned int shift, unsigned int ncycles)
+{
+	unsigned int val;
+	int ret;
+
+	if (shift != ATMEL_SMC_NWE_SHIFT && shift != ATMEL_SMC_NCS_WR_SHIFT &&
+	    shift != ATMEL_SMC_NRD_SHIFT && shift != ATMEL_SMC_NCS_RD_SHIFT)
+		return -EINVAL;
+
+	/*
+	 * The formula described in atmel datasheets (section "SMC Setup
+	 * Register"):
+	 *
+	 * ncycles = (128 * xx_SETUP[5]) + xx_SETUP[4:0]
+	 */
+	ret = atmel_smc_cs_encode_ncycles(ncycles, 5, 1, 128, &val);
+	conf->setup &= ~GENMASK(shift + 7, shift);
+	conf->setup |= val << shift;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_set_setup);
+
+/**
+ * atmel_smc_cs_conf_set_pulse - set the SMC CS conf xx_PULSE parameter to a
+ *				 specific value
+ * @conf: SMC CS conf descriptor
+ * @shift: the position of the xx_PULSE field in the PULSE register
+ * @ncycles: value (expressed in MCK clk cycles) to assign to this xx_PULSE
+ *	     parameter
+ *
+ * This function encodes the @ncycles value as described in the datasheet
+ * (section "SMC Pulse Register"), and then stores the result in the
+ * @conf->setup field at @shift position.
+ *
+ * Returns -EINVAL if @shift is invalid, -ERANGE if @ncycles does not fit in
+ * the field, and 0 otherwise.
+ */
+int atmel_smc_cs_conf_set_pulse(struct atmel_smc_cs_conf *conf,
+				unsigned int shift, unsigned int ncycles)
+{
+	unsigned int val;
+	int ret;
+
+	if (shift != ATMEL_SMC_NWE_SHIFT && shift != ATMEL_SMC_NCS_WR_SHIFT &&
+	    shift != ATMEL_SMC_NRD_SHIFT && shift != ATMEL_SMC_NCS_RD_SHIFT)
+		return -EINVAL;
+
+	/*
+	 * The formula described in atmel datasheets (section "SMC Pulse
+	 * Register"):
+	 *
+	 * ncycles = (256 * xx_PULSE[6]) + xx_PULSE[5:0]
+	 */
+	ret = atmel_smc_cs_encode_ncycles(ncycles, 6, 1, 256, &val);
+	conf->pulse &= ~GENMASK(shift + 7, shift);
+	conf->pulse |= val << shift;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_set_pulse);
+
+/**
+ * atmel_smc_cs_conf_set_cycle - set the SMC CS conf xx_CYCLE parameter to a
+ *				 specific value
+ * @conf: SMC CS conf descriptor
+ * @shift: the position of the xx_CYCLE field in the CYCLE register
+ * @ncycles: value (expressed in MCK clk cycles) to assign to this xx_CYCLE
+ *	     parameter
+ *
+ * This function encodes the @ncycles value as described in the datasheet
+ * (section "SMC Cycle Register"), and then stores the result in the
+ * @conf->setup field at @shift position.
+ *
+ * Returns -EINVAL if @shift is invalid, -ERANGE if @ncycles does not fit in
+ * the field, and 0 otherwise.
+ */
+int atmel_smc_cs_conf_set_cycle(struct atmel_smc_cs_conf *conf,
+				unsigned int shift, unsigned int ncycles)
+{
+	unsigned int val;
+	int ret;
+
+	if (shift != ATMEL_SMC_NWE_SHIFT && shift != ATMEL_SMC_NRD_SHIFT)
+		return -EINVAL;
+
+	/*
+	 * The formula described in atmel datasheets (section "SMC Cycle
+	 * Register"):
+	 *
+	 * ncycles = (xx_CYCLE[8:7] * 256) + xx_CYCLE[6:0]
+	 */
+	ret = atmel_smc_cs_encode_ncycles(ncycles, 7, 2, 256, &val);
+	conf->cycle &= ~GENMASK(shift + 15, shift);
+	conf->cycle |= val << shift;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_set_cycle);
+
+/**
+ * atmel_smc_cs_conf_apply - apply an SMC CS conf
+ * @regmap: the SMC regmap
+ * @cs: the CS id
+ * @conf: the SMC CS conf to apply
+ *
+ * Applies an SMC CS configuration.
+ * Only valid on at91sam9/avr32 SoCs.
+ */
+void atmel_smc_cs_conf_apply(struct regmap *regmap, int cs,
+			     const struct atmel_smc_cs_conf *conf)
+{
+	regmap_write(regmap, ATMEL_SMC_SETUP(cs), conf->setup);
+	regmap_write(regmap, ATMEL_SMC_PULSE(cs), conf->pulse);
+	regmap_write(regmap, ATMEL_SMC_CYCLE(cs), conf->cycle);
+	regmap_write(regmap, ATMEL_SMC_MODE(cs), conf->mode);
+}
+EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_apply);
+
+/**
+ * atmel_hsmc_cs_conf_apply - apply an SMC CS conf
+ * @regmap: the HSMC regmap
+ * @cs: the CS id
+ * @layout: the layout of registers
+ * @conf: the SMC CS conf to apply
+ *
+ * Applies an SMC CS configuration.
+ * Only valid on post-sama5 SoCs.
+ */
+void atmel_hsmc_cs_conf_apply(struct regmap *regmap,
+			      const struct atmel_hsmc_reg_layout *layout,
+			      int cs, const struct atmel_smc_cs_conf *conf)
+{
+	regmap_write(regmap, ATMEL_HSMC_SETUP(layout, cs), conf->setup);
+	regmap_write(regmap, ATMEL_HSMC_PULSE(layout, cs), conf->pulse);
+	regmap_write(regmap, ATMEL_HSMC_CYCLE(layout, cs), conf->cycle);
+	regmap_write(regmap, ATMEL_HSMC_TIMINGS(layout, cs), conf->timings);
+	regmap_write(regmap, ATMEL_HSMC_MODE(layout, cs), conf->mode);
+}
+EXPORT_SYMBOL_GPL(atmel_hsmc_cs_conf_apply);
+
+/**
+ * atmel_smc_cs_conf_get - retrieve the current SMC CS conf
+ * @regmap: the SMC regmap
+ * @cs: the CS id
+ * @conf: the SMC CS conf object to store the current conf
+ *
+ * Retrieve the SMC CS configuration.
+ * Only valid on at91sam9/avr32 SoCs.
+ */
+void atmel_smc_cs_conf_get(struct regmap *regmap, int cs,
+			   struct atmel_smc_cs_conf *conf)
+{
+	regmap_read(regmap, ATMEL_SMC_SETUP(cs), &conf->setup);
+	regmap_read(regmap, ATMEL_SMC_PULSE(cs), &conf->pulse);
+	regmap_read(regmap, ATMEL_SMC_CYCLE(cs), &conf->cycle);
+	regmap_read(regmap, ATMEL_SMC_MODE(cs), &conf->mode);
+}
+EXPORT_SYMBOL_GPL(atmel_smc_cs_conf_get);
+
+/**
+ * atmel_hsmc_cs_conf_get - retrieve the current SMC CS conf
+ * @regmap: the HSMC regmap
+ * @cs: the CS id
+ * @layout: the layout of registers
+ * @conf: the SMC CS conf object to store the current conf
+ *
+ * Retrieve the SMC CS configuration.
+ * Only valid on post-sama5 SoCs.
+ */
+void atmel_hsmc_cs_conf_get(struct regmap *regmap,
+			    const struct atmel_hsmc_reg_layout *layout,
+			    int cs, struct atmel_smc_cs_conf *conf)
+{
+	regmap_read(regmap, ATMEL_HSMC_SETUP(layout, cs), &conf->setup);
+	regmap_read(regmap, ATMEL_HSMC_PULSE(layout, cs), &conf->pulse);
+	regmap_read(regmap, ATMEL_HSMC_CYCLE(layout, cs), &conf->cycle);
+	regmap_read(regmap, ATMEL_HSMC_TIMINGS(layout, cs), &conf->timings);
+	regmap_read(regmap, ATMEL_HSMC_MODE(layout, cs), &conf->mode);
+}
+EXPORT_SYMBOL_GPL(atmel_hsmc_cs_conf_get);
+
+static const struct atmel_hsmc_reg_layout sama5d3_reg_layout = {
+	.timing_regs_offset = 0x600,
+};
+
+static const struct atmel_hsmc_reg_layout sama5d2_reg_layout = {
+	.timing_regs_offset = 0x700,
+};
+
+static const struct udevice_id atmel_smc_ids[] = {
+	{ .compatible = "atmel,at91sam9260-smc", .data = (ulong)0 },
+	{ .compatible = "atmel,sama5d3-smc", .data = (ulong)&sama5d3_reg_layout },
+	{ .compatible = "atmel,sama5d2-smc", .data = (ulong)&sama5d2_reg_layout },
+	{ /* sentinel */ },
+};
+
+/**
+ * atmel_hsmc_get_reg_layout - retrieve the layout of HSMC registers
+ * @np: the HSMC regmap
+ *
+ * Retrieve the layout of HSMC registers.
+ *
+ * Returns NULL in case of SMC, a struct atmel_hsmc_reg_layout pointer
+ * in HSMC case, otherwise ERR_PTR(-EINVAL).
+ */
+const struct atmel_hsmc_reg_layout *
+atmel_hsmc_get_reg_layout(ofnode np)
+{
+	int i;
+	const struct udevice_id *match;
+	const char *name;
+	int len;
+
+	name = ofnode_get_property(np, "compatible", &len);
+
+	for (i = 0; i < ARRAY_SIZE(atmel_smc_ids); i++) {
+		if (!strcmp(name, atmel_smc_ids[i].compatible)) {
+			match = &atmel_smc_ids[i];
+			break;
+		}
+	}
+
+	return match ? (struct atmel_hsmc_reg_layout *)match->data : ERR_PTR(-EINVAL);
+}