SH7751 have 15 level external interrupt.
It is typically connected to the CPU through a priority encoder
that can suppress requests.
This driver provides a way to control those hardware with irqchip.

Signed-off-by: Yoshinori Sato <ys...@users.sourceforge.jp>
---
 drivers/irqchip/Kconfig                 |   7 +
 drivers/irqchip/Makefile                |   2 +
 drivers/irqchip/irq-renesas-sh7751irl.c | 221 ++++++++++++++++++++++++
 3 files changed, 230 insertions(+)
 create mode 100644 drivers/irqchip/irq-renesas-sh7751irl.c

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 33badb5b4f00..7670fcd6757d 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -698,4 +698,11 @@ config RENESAS_SH7751_INTC
          Support for the Renesas SH7751 On-chip interrupt controller.
          And external interrupt encoder for some targets.
 
+config RENESAS_SH7751IRL_INTC
+       bool "Renesas SH7751 based target IRL encoder support."
+       depends on RENESAS_SH7751_INTC
+       help
+         Support for External Interrupt encoder
+         on the some Renesas SH7751 based target.
+
 endmenu
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 51855034a895..bc21d65441f2 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -122,3 +122,5 @@ obj-$(CONFIG_APPLE_AIC)                     += 
irq-apple-aic.o
 obj-$(CONFIG_MCHP_EIC)                 += irq-mchp-eic.o
 obj-$(CONFIG_SUNPLUS_SP7021_INTC)      += irq-sp7021-intc.o
 obj-$(CONFIG_RENESAS_SH7751_INTC)      += irq-renesas-sh7751.o
+obj-$(CONFIG_RENESAS_SH7751IRL_INTC)   += irq-renesas-sh7751irl.o
+
diff --git a/drivers/irqchip/irq-renesas-sh7751irl.c 
b/drivers/irqchip/irq-renesas-sh7751irl.c
new file mode 100644
index 000000000000..5990f2cd9a3d
--- /dev/null
+++ b/drivers/irqchip/irq-renesas-sh7751irl.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SH7751 based board external interrupt level encoder driver
+ * (Renesas RTS7751R2D / IO DATA DEVICE LANDISK, USL-5P)
+ *
+ * Copyright (C) 2023 Yoshinori Sato
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irqdomain.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+
+struct sh7751irl_intc_priv {
+       struct irq_domain *irq_domain;
+       void __iomem      *base;
+       unsigned int      width;
+       bool              invert;
+       u32               enable_bit[NR_IRL];
+};
+
+static inline unsigned long get_reg(void __iomem *addr, unsigned int w)
+{
+       switch (w) {
+       case 8:
+               return __raw_readb(addr);
+       case 16:
+               return __raw_readw(addr);
+       case 32:
+               return __raw_readl(addr);
+       default:
+               /* The size is checked when reading the properties. */
+               pr_err("%s: Invalid width %d", __FILE__, w);
+               return 0;
+       }
+}
+
+static inline void set_reg(void __iomem *addr, unsigned int w, unsigned long 
val)
+{
+       switch (w) {
+       case 8:
+               __raw_writeb(val, addr);
+               break;
+       case 16:
+               __raw_writew(val, addr);
+               break;
+       case 32:
+               __raw_writel(val, addr);
+               break;
+       default:
+               pr_err("%s: Invalid width %d", __FILE__, w);
+       }
+}
+
+static inline struct sh7751irl_intc_priv *irq_data_to_priv(struct irq_data 
*data)
+{
+       return data->domain->host_data;
+}
+
+static void irl_endisable(struct irq_data *data, unsigned int enable)
+{
+       struct sh7751irl_intc_priv *priv;
+       unsigned long val;
+       unsigned int irl;
+
+       priv = irq_data_to_priv(data);
+       irl = irqd_to_hwirq(data) - IRL_BASE_IRQ;
+
+       if (irl < NR_IRL && priv->enable_bit[irl] < priv->width) {
+               if (priv->invert)
+                       enable = !enable;
+
+               val = get_reg(priv->base, priv->width);
+               if (enable)
+                       set_bit(priv->enable_bit[irl], &val);
+               else
+                       clear_bit(priv->enable_bit[irl], &val);
+               set_reg(priv->base, priv->width, val);
+       } else {
+               pr_err("%s: Invalid register define in IRL %u", __FILE__, irl);
+       }
+}
+
+static void sh7751irl_intc_disable_irq(struct irq_data *data)
+{
+       irl_endisable(data, 0);
+}
+
+static void sh7751irl_intc_enable_irq(struct irq_data *data)
+{
+       irl_endisable(data, 1);
+}
+
+static struct irq_chip sh7751irl_intc_chip = {
+       .name           = "SH7751IRL-INTC",
+       .irq_enable     = sh7751irl_intc_enable_irq,
+       .irq_disable    = sh7751irl_intc_disable_irq,
+};
+
+static int sh7751irl_intc_map(struct irq_domain *h, unsigned int virq,
+                              irq_hw_number_t hw_irq_num)
+{
+       irq_set_chip_and_handler(virq, &sh7751irl_intc_chip, handle_level_irq);
+       irq_get_irq_data(virq)->chip_data = h->host_data;
+       irq_modify_status(virq, IRQ_NOREQUEST, IRQ_NOPROBE);
+       return 0;
+}
+
+static int sh7751irl_intc_translate(struct irq_domain *domain,
+                              struct irq_fwspec *fwspec, unsigned long *hwirq,
+                              unsigned int *type)
+{
+       if (fwspec->param[0] > NR_IRL)
+               return -EINVAL;
+
+       switch (fwspec->param_count) {
+       case 2:
+               *type = fwspec->param[1];
+               fallthrough;
+       case 1:
+               *hwirq = fwspec->param[0] + IRL_BASE_IRQ;
+               break;
+       default:
+               return -EINVAL;
+       }
+       return 0;
+}
+
+static const struct irq_domain_ops sh7751irl_intc_domain_ops = {
+       .map = sh7751irl_intc_map,
+       .translate = sh7751irl_intc_translate,
+};
+
+static int __init load_irl_bit(struct device_node *node, struct 
sh7751irl_intc_priv *priv)
+{
+       struct property *enable_map;
+       const __be32 *p;
+       u32 nr_bits, bit;
+       u32 irl;
+       int ret;
+
+       /* Fill in unused */
+       memset(priv->enable_bit, ~0, sizeof(priv->enable_bit));
+
+       enable_map = of_find_property(node, "renesas,enable-reg", &nr_bits);
+       if (IS_ERR(enable_map))
+               return PTR_ERR(enable_map);
+
+       nr_bits /= sizeof(u32);
+       if (nr_bits > priv->width)
+               return -EINVAL;
+
+       ret = nr_bits;
+       p = NULL;
+       for (bit = nr_bits; bit > 0; bit--) {
+               p = of_prop_next_u32(enable_map, p, &irl);
+               if (p == NULL || irl > NR_IRL)
+                       return -EINVAL;
+               if (irl == NR_IRL)
+                       /* IRL15 is unassined bit */
+                       continue;
+               priv->enable_bit[irl] = bit - 1;
+       }
+       return ret;
+}
+
+static int __init sh7751irl_init(struct device_node *node, struct device_node 
*parent)
+{
+       struct sh7751irl_intc_priv *priv;
+       struct resource res;
+       struct irq_domain *d;
+       void __iomem *base;
+       int ret = 0;
+
+       if (of_address_to_resource(node, 0, &res))
+               return -EINVAL;
+       if (resource_size(&res) > 4)
+               return -EINVAL;
+
+       base = ioremap(res.start, resource_size(&res));
+       if (!base)
+               return -EINVAL;
+
+       priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return -ENOMEM;
+
+       priv->base = base;
+       priv->width = 8 << resource_size(&res);
+
+       ret = load_irl_bit(node, priv);
+       if (ret < 0) {
+               pr_err("%pOFP: Invalid register define.\n", node);
+               goto error;
+       }
+
+       d = irq_domain_add_tree(node, &sh7751irl_intc_domain_ops, priv);
+       if (d == NULL) {
+               pr_err("%pOFP: cannot initialize irq domain\n", node);
+               ret = -ENOMEM;
+               goto error;
+       }
+
+       priv->irq_domain = d;
+       irq_domain_update_bus_token(d, DOMAIN_BUS_WIRED);
+       pr_info("%pOFP: SH7751 External Interrupt encoder (input=%d)", node, 
ret);
+       return 0;
+error:
+       kfree(priv);
+       return ret;
+}
+
+IRQCHIP_DECLARE(renesas_sh7751_irl, "renesas,sh7751-irl-ext", sh7751irl_init);
-- 
2.39.2

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