This patch adds a helper function to calculate the ring configuration
of the controller based on various constraints, like available RAM,
size of RX and TX objects, CAN-mode, number of FIFOs and FIFO depth.
Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
---
drivers/net/can/spi/mcp251xfd/Makefile | 1 +
drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.c | 97 +++++++++++++++++++
drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.h | 57 +++++++++++
3 files changed, 155 insertions(+)
create mode 100644 drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.c
create mode 100644 drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.h
diff --git a/drivers/net/can/spi/mcp251xfd/Makefile b/drivers/net/can/spi/mcp251xfd/Makefile
index a83d685d64e0..10c4f886d1f7 100644
--- a/drivers/net/can/spi/mcp251xfd/Makefile
+++ b/drivers/net/can/spi/mcp251xfd/Makefile
@@ -6,6 +6,7 @@ mcp251xfd-objs :=
mcp251xfd-objs += mcp251xfd-chip-fifo.o
mcp251xfd-objs += mcp251xfd-core.o
mcp251xfd-objs += mcp251xfd-crc16.o
+mcp251xfd-objs += mcp251xfd-ram.o
mcp251xfd-objs += mcp251xfd-regmap.o
mcp251xfd-objs += mcp251xfd-ring.o
mcp251xfd-objs += mcp251xfd-rx.o
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.c
new file mode 100644
index 000000000000..6e7293e50d2c
--- /dev/null
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// mcp251xfd - Microchip MCP251xFD Family CAN controller driver
+//
+// Copyright (c) 2021, 2022 Pengutronix,
+// Marc Kleine-Budde <kernel@xxxxxxxxxxxxxx>
+//
+
+#include "mcp251xfd-ram.h"
+
+static inline u8 can_ram_clamp(const struct can_ram_config *config,
+ const struct can_ram_obj_config *obj,
+ u8 val)
+{
+ u8 max;
+
+ max = min_t(u8, obj->max, obj->fifo_num * config->fifo_depth);
+ return clamp(val, obj->min, max);
+}
+
+static u8
+can_ram_rounddown_pow_of_two(const struct can_ram_config *config,
+ const struct can_ram_obj_config *obj, u8 val)
+{
+ u8 fifo_num = obj->fifo_num;
+ u8 ret = 0, i;
+
+ val = can_ram_clamp(config, obj, val);
+
+ for (i = 0; i < fifo_num && val; i++) {
+ u8 n;
+
+ n = min_t(u8, rounddown_pow_of_two(val),
+ config->fifo_depth);
+
+ /* skip small FIFOs */
+ if (n < obj->fifo_depth_min)
+ return ret;
+
+ ret += n;
+ val -= n;
+ }
+
+ return ret;
+}
+
+void can_ram_get_layout(struct can_ram_layout *layout,
+ const struct can_ram_config *config,
+ const struct ethtool_ringparam *ring,
+ const bool fd_mode)
+{
+ u8 num_rx, num_tx;
+ u16 ram_free;
+
+ /* default CAN */
+
+ num_tx = config->tx.def[fd_mode];
+ num_tx = can_ram_rounddown_pow_of_two(config, &config->tx, num_tx);
+
+ ram_free = config->size;
+ ram_free -= config->tx.size[fd_mode] * num_tx;
+
+ num_rx = ram_free / config->rx.size[fd_mode];
+
+ layout->default_rx = can_ram_rounddown_pow_of_two(config, &config->rx, num_rx);
+ layout->default_tx = num_tx;
+
+ /* MAX CAN */
+
+ ram_free = config->size;
+ ram_free -= config->tx.size[fd_mode] * config->tx.min;
+ num_rx = ram_free / config->rx.size[fd_mode];
+
+ ram_free = config->size;
+ ram_free -= config->rx.size[fd_mode] * config->rx.min;
+ num_tx = ram_free / config->tx.size[fd_mode];
+
+ layout->max_rx = can_ram_rounddown_pow_of_two(config, &config->rx, num_rx);
+ layout->max_tx = can_ram_rounddown_pow_of_two(config, &config->tx, num_tx);
+
+ /* cur CAN */
+
+ if (ring) {
+ num_rx = can_ram_rounddown_pow_of_two(config, &config->rx, ring->rx_pending);
+
+ ram_free = config->size - config->rx.size[fd_mode] * num_rx;
+ num_tx = ram_free / config->tx.size[fd_mode];
+ num_tx = min_t(u8, ring->tx_pending, num_tx);
+ num_tx = can_ram_rounddown_pow_of_two(config, &config->tx, num_tx);
+
+ layout->cur_rx = num_rx;
+ layout->cur_tx = num_tx;
+ } else {
+ layout->cur_rx = layout->default_rx;
+ layout->cur_tx = layout->default_tx;
+ }
+}
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.h b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.h
new file mode 100644
index 000000000000..c998a033c9cb
--- /dev/null
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-ram.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * mcp251xfd - Microchip MCP251xFD Family CAN controller driver
+ *
+ * Copyright (c) 2021, 2022 Pengutronix,
+ * Marc Kleine-Budde <kernel@xxxxxxxxxxxxxx>
+ */
+
+#ifndef _MCP251XFD_RAM_H
+#define _MCP251XFD_RAM_H
+
+#include <linux/ethtool.h>
+
+#define CAN_RAM_NUM_MAX (-1)
+
+enum can_ram_mode {
+ CAN_RAM_MODE_CAN,
+ CAN_RAM_MODE_CANFD,
+ __CAN_RAM_MODE_MAX
+};
+
+struct can_ram_obj_config {
+ u8 size[__CAN_RAM_MODE_MAX];
+
+ u8 def[__CAN_RAM_MODE_MAX];
+ u8 min;
+ u8 max;
+
+ u8 fifo_num;
+ u8 fifo_depth_min;
+};
+
+struct can_ram_config {
+ const struct can_ram_obj_config rx;
+ const struct can_ram_obj_config tx;
+
+ u16 size;
+ u8 fifo_depth;
+};
+
+struct can_ram_layout {
+ u8 default_rx;
+ u8 default_tx;
+
+ u8 max_rx;
+ u8 max_tx;
+
+ u8 cur_rx;
+ u8 cur_tx;
+};
+
+void can_ram_get_layout(struct can_ram_layout *layout,
+ const struct can_ram_config *config,
+ const struct ethtool_ringparam *ring,
+ const bool fd_mode);
+
+#endif
--
2.35.1
